Er... uh... um... well... you see...
1) Upper Canada was founded in 1791. In the ARW, it was part of Quebec.
2) During the ARW, it was a howling wilderness. A couple of seigneuries, along the Ottawa, and easternmost stretch of the St Lawrence before Montreal; not much else.
3) York was founded in 1793 by
Loyalists. The UELs, who were the ones
even more Loyalist than the others.
4) A heavy toll at Abraham means more regulars brought over from Britain or the Colonies, not militia levies from the (nonexistent) Anglo settlers of Quebec.
5) More to the point, once Montcalm (and, since we're assuming a British Quebec here,
de Levis) are defeated, there's no threat to British control of Quebec, really. The Quebecois, from 1760 -> ~1900, are more notable for their complete indifference to who ran the place than anything else.
6) More really, really to the point, Ontario was only marginally more European-settled than Wyoming at this time. It won't revolt (and if it does, it will
literally be unnoticed, since its Anglo population was something like 2).
In short... uh, no. Implausible doesn't cut it; NS could have been the 14th colony but the nonexistent "colony" of Upper Canada certainly couldn't.
EDIT: Er, also, "the Regular Army is suppressing things ineffectively!" is just about the
worst standard for revolt I've ever heard...
