Depends, and also depends on the morality of the Redcaps involved. The "precedent," as it were, is that Mercere himself lost his Gift after being recognized as a magus, and created a special tradition of the Order just for that. Whether the Redcaps want that to be a special Mercere thing, or a general rule for those whose Gifts are destroyed, is going to vary from Mercere to Mercere. (The only House that votes in lockstep, remember, is Tremere.)
However, on reflection, I think it's likely a moot point. Nobody will challenge the Jerbiton Primus' right to decide who's a Jerbiton, or the Ex Miscellanea Primus' right to accept anyone outcast from other Houses. It'd take a Tribunal decision to renounce the magus from the Order, doing so without Wizard's Marching him would be unprecedented, and the majority of Quaesitores aren't in the business of kicking hornet's nests when sleeping dogs can be let lie. If both Jerbiton and Ex Miscellanea said that the magus was out (unlikely), then most Quaesitores would just pretend that the magus had never been a magus.
Given that a redcap that goes against the leadership can be declared orbus and an orbus redcap will have a hard time finding a place in another house (even ex miscellanea), I am not so sure that Tremere are the only ones that use block voting....
I'm intending the discussion to play out over an exceptional tribunal meeting (caused by the sacking of Constantinople in 1204)... And this has provided the material for the debating positions!
I can see the gain, if he stays in the order, is his vote/sigil being useful to whoever he ends up with. Hoping the final answer might get tilted by the pcs, as I find that a more involving solution.
I like the idea that his apprentice (s)and sodales will consider pushing to declare him officially dead, to claim his lab and goods... Which is just nasty!
As mentioned by Erik Dahl, House Jerbiton accept non-gifted members 'Larta magi' with training by Redcap, a full magician losing their gift has no need for such training as they are already fully trained. To suggest that a fully gifted magician who loses their gift would be less welcome in the house than a Larta magi seems a bit absurd to me.
With Redcaps, non-hermetic magi of house ex-miscellania and larta magi, you are talking about at least 200 members of the Order without the gift spread around the different Tribunals. Roughly 10% of all sworn members of the Order. I don't think anyone moving to expel, march or perform wizard's war on a magi solely for losing their gift would last long before someone declares wizards war back against them in revenge.
A full magi should have sufficient favours, resources etc. before losing the gift to parlay into commissioning several magical items to protect himself with, as well as purchasing longevity potions. It might be wise for him to volunteer to no longer vote in tribunal out of respect for his lesser status, and suggesting to his sodales in his covenant that as he no longer has a gift and can no longer improve his arts or invent spells he would be happy to volunteer to perform a lot of their covenant service he is still capable of would probably go down well too.
I think that, by default, you have to have the Gift to be adopted Ex Miscellanea from outside the Order, because the Gift is required to learn Parma Magica (and more than anything else, the Parma is the mark that says "I am a magus of the Order of Hermes"). I could be wrong.
If I were going to speak against the idea of an ex-magus being allowed to remain a magus, I would defend the decision on the grounds that with the loss of their Gift, the magus is unable to defend their position against certamen or War. Tremere and Tytalus would almost have to back that interpretation.
You can have a champion for certamen, and war... well, you can always also find a champion for that. IMO it is a thing on how vocal the magus is. If he recognizes his reduced role in the Order (like Mercere did) he might stay around, but he will not be treated as a "proper" magus. Still, he is a valuable resource for sure (write books, act as envoy in front of mundanes, research essoteric stuff that does not require the gift but is much more useful if you have a hermetic magic frame of mind... ).
I know, but it's how I would argue it. (Again, Tribunal politics; this person has no business voting their sigil if they can't defend it.)
On the other hand, if the magus chose to try to stand their ground, and had allies who were willing to defend their position, and the vote fell in their favor, it's entirely possible that they'd be in position to remain as magi despite not being able to cast spells. They might begin studying non-Gifted magic to make up for their loss and establish themselves in a niche, focus on bookwriting and Companionly stuff, or (of course) seek a way to restore their Gift. (Pity that the only canonical way to create the Gift involves the Maleficia...)
HoH Societas book gives the option of Gifted Companion non-Hermetic magi, and gives an example of the Scinnfolk tradition, but they also have all the Hedge Magic traditions joined like Graugach, of which it seems there are more non-gifted than gifted. I was guessing of the 180 magi of Ex-Misc that roughly 30-40 would be non-gifted.
As for Larta being buried in 5th edition, weirdly enough I thought they were a 5th edition invention, maybe I am remembering wrong. Gotta check.
Huh. I would imagine that that would require ex Miscellanea to have a procedure for such magi, as "no Parma Magica" is a fairly nasty weakness unless their tradition provides a similarly all-encompassing defense (a Guardian Angel or something).
One of the things to consider is that the Hedge Magics book gives Initiation scripts for Ungifted casters, the examples given were to be initiated into all of the magics of each particular tradition.
Not too much of a reach to imagine that Ex Misc have come up with an initiation for Parma Magica, just they would end up with some serious flaws as a trade off.
