It's an election year. Trudeau wants a second term. But he's turned off much of his traditional centrist base (corruption allegations, many of us realizing he's actually not very smart, etc). He's got new leaders on both the Conservative party (the right) and the NDP (the left) who are trying to squeeze the votes out of middle.

He knows he's got little chance of winning back anyone right of center- the Conservatives will take those votes most likely- so he's going after the votes on the left.

The plastic ban and the finally reopened marine mammal captivity bans are both moves to appeal to the environmentalist left. He'll probably also try to win over unions as much as he can. He wants to eat the NDP votes and hope it's enough to make up his loss on the right.

And I'll still probably vote for him again because the alternatives are somehow worse.