It doesn't really though. The only problem it outlines is that it doesn't pay a living wage. It says nothing about why it's a problem that people with high incomes also get this (other than it's unfair). It then suggests making it more complicated (increasing overhead) so that poor people can get more.
But it's much simpler than that. Just pay everyone more. Make it an actual basic income at living wage, and adjust the tax brackets appropriately.
Then expand it to include everyone instead of just seniors.
For some added context, this has been going on for years from all parties. Maybe this year was not the most amicable environment to do this in, and maybe these particular slogans were in bad taste, but I don't think this is as egregious as everyone is saying.
https://www.cbc.ca/news/politics/political-party-convention-gimmicks-1.2530848