I've always disliked the notion that there are PC-specific rules. As is, we have confidence points to make PCs "cooler" than grogs. I freely admit it comes down to the play style you like; to me, the notion that, by virtues of being PCs, characters will be better at any cool endeavor they choose to undertake, whether making their own mystery cult or trying to score Hermetic Breakthroughs takes away from the satisfaction of the game world, because it feels like PC achievements have to be viewed in terms of them being "born" special. Thankfully, I have not noticed any explicit "but only PCs can do this" guidelines in the 5th ed AM line.
As for the in-game rationalization... well, for one, don't forget that the canon sizes of the houses are pretty small. (Though they're up from 4th ed, when house Bonisagus had less than three dozen, I think.) And half the house is political.
Beside that, I would say that for an average magus, 2 seasons a year in research plus 2 in arts increase is... so optimal as to be funny. Tribunals, adventures, House Bonisagus meetings, writing, teaching an apprentice... all of these are activities a Bonisagus can conceivably get roped into. All are avoidable, I suppose, but a magus who manages to dedicate himself so completely to nothing but work is an exceptional one, I think, even within a house of researchers.
And, as rightly pointed out, Original Research does tend to occasionally cause problematic chaos in one's lab.
Finally, while you stipulated using the rules as written, I must admit that I was completely moved by Matt Ryan and co in the below thread about the OR rules, and consider Matt's modifications to the OR rules as written near-mandatory when OR comes up in my saga.
https://forum.atlas-games.com/t/original-research-rules-in-5th-edition/499/10