> No, you can do things that benefit you electorally, but are also just the right thing to do. Changing the voting system from FPTP would obviously benefit parties other than the major ones, but that doesn't mean it'd be wrong for those parties to do it if they got into power

You're reinforcing my point.

Minor parties (who might collectively be popular with the electorate) will never be able to change the voting methodology to their advantage because FPTP keeps the incumbents in place, and only the incumbents have the power to choose the voting system. So democracy suffers and the incumbents benefit.

Similarly, in this case, allowing children to vote helps the incumbents stay in place despite their party, and their leader being deeply unpopular with the electorate overall. So democracy suffers and the incumbents benefit.