Agreed. In an over-simplification,
- first past the post is the best for the Conservatives. (It was best for the Liberals before the Reform & Conservatives merged).
- single transferable is the best for the Liberals
- mixed-member proportional is the best for the NDP
Trudeau thought the electoral commission would give him the STV he wanted, but it was going to deliver MMP that would pretty much guarantee that he would have to coalition with the NDP. So he nixed it. He ended up with an NDP coalition anyways, so he didn't gain anything through the nixing. Instead FPTP is going to result in a Conservative landslide in 2025.