The reason it's a law in every other province is that FMJ's wound game, and ultimately kill it days, weeks and often months later because those who use them don't know any better and think that bullets are bullets, and the cheaper the better.
That is a total load of crap. What it really tells me is you and your well meaning buddy don't know what the hell you're talking about, and really haven't seen anything shot with solids in your life. You're running on "everybody knows" information - which is basically that "everybody knows" shyte.
I offer two things for your consideration. First, hunters in Africa - you know, the families actually living out in the bush, not the ones showing up for a $50,000 safari once in their life - have been shooting game with solids for generations. A friend of mine - a woman - said she never fired anything other than solids out of her .375 H&H until they fled the former Rhodesia for Canada. She has probably shot more game in her life than any dozen of us here, and she told me that both the .303 and the .375 worked just fine around their property, thank you very much.
Second, when we were over in Yugo, we shot the local version of elk and feral pigs for the locals who usually had little or nothing to eat, whenever we got a chance. As we weren't issued premium hunting ammo, we shot them with ball out of the C7A1's and C6's when we had a chance to unlimber the gun. So I have seen some pretty big animals tipped over with ball ammo, and here's what I saw:
Contrary to your claim that they run off to die days, weeks, and months later, they pretty much die where they're shot. I actually didn't see all that much difference than I do with my hunting rounds - and just to assuage your fears, I hunt with Barnes X's pretty much exclusively. If you think shooting pigs is no big deal, you haven't seen the size of the pigs over there.
I also saw some pretty impressive terminal performance when we gutted them. Frankly, if you didn't know what kind of ammunition was used, I doubt very much if you could tell which critter was hit with premium expanding and what was hit by ball - ball upsets and does a pretty good job, actually.
So I'll match what I have personally seen against the theories of you and your friend any day. That doesn't mean I am falling all over myself to use FMJ instead of what shoots so well in my rifle. But spreading a load of BS around about what solids supposedly do and how they leave animals wandering around wounded for weeks on end is irresponsible nonsense. We have PETA and their fellow travellers spreading enough BS without hunters helpfully adding to it.
Finally, I agree that the last thing we need in this country is yet more regulatory laws regimenting every damned breath and step we take in life. On the other hand, I also believe that hunters have to obey game laws, even the ones they think are nonsense, because of the fact we're in the public eye and so open to criticism.