p47 of Realms of Power: Magic says that if Age Quicly is taken by a creature with magical might, they make one roll a year. Basically it means the dwarves would age like humans would.
I wrote a long explanation of how if instead of providing 7XP to spend wherever you wanted, you used extremly slow method of character advancement, you got grogs with lots of skills in the 6 or 7 range rather than one skill in the 12 range, and that is pretty special too. However, when I went to post it, the system kicked me out and I lost it.
As for why the magical dwarves have stayed in the regio covenant for 60 years...they have been living there all their lives, if they leave they face acclimation, and as magical humans must have the monstrous appearance flaw, it is difficult to make their way in the world at large. As for why they would study Single Weapon, well, if the autocrat has assigned them to work as guards, this is how they make their living.
What makes something a magical creature is having a Magical Might score. The explanation of the Age Quickly Flaw in Realms of Power, Magic explains what happens when you apply that flaw to something with a magical might score. Therefore, it is possible for magical creatures to age, just not grog level magical creatures, since they can't take Major Flaws.
Thanks for point that out to me, I wasn't aware that RoP:Magic changed the flaw. The change wasn't carried through to MetaCreator, where I often review the nature of flaws, my mistake. My statement was, that if you need to age these characters, they can't be magic creatures, and that still stands if they can't take a major flaw. But that can also be something of a solution to your problem; they aren't actually magical anymore, they age normally and they are mundane.
Saying that I can have mundane grogs that age instead of the magical dwarf grogs that age is missing the point. Of course I can have mundane grogs. I could even have grogs who have a lesser malediction that makes them take on the monstrous appearance consistent with being a dwarf while being a dwarf. My complaint is that under RAW, I can't depower the dwarves so that they are closer to mundane grogs, whereas if they were considered more important characters for the story, I could.
Along with not aging, magical creatures are immune to warping. Having grogs that can be under a constant mystic effect or live in a high level aura without warping is very useful.
I may be missing this, but I do not see anywhere that indicates that grog level magical creatures cannot take major inferiorities or qualities, just not major flaws or virtues.
I didn't read the whole tread, but here's my though on how to have magical dwarven grogs without breaking the rules.
Create a new minor virtue (or flaw) called appropriatedly for your saga, such as "Magical Dwarf of Higgs". In that minor virtue, package the standard stuff for that magical race so that it balances out to the power of one minor virtue (or flaw), including the appropriate major virtue(s) and/or flaw(s).