I'd agree with you, but having watched what the US backslide, this is necessary. It's important for centrists and leftists to make sure that it's very clear what conservatives are and what they stand for. If they'd just voted yes and moved on--since this is a symbolic vote--this would be a non-issue. But they didn't; they virtue-signalled to their base.

It's also why Steven Harper, of all people, would nuke from orbit any CPC MP that would raise the spectre of abortion (and why, when he let anti-Muslim bigotry run rampant it cost him) and it's why Poillievre is playing a very dangerous game courting that same vote.