I think the framing that "individual bad actors must be regulated for the good of the collective" is wrong here. In my opinion, what GP is saying is more along the line of "powerful actors must be regulated for the good of the collective powerless people".
When you look at it like that, then what Google and Apple is doing does not fit this point of view. They are (extremely) powerful entities imposing themselves on the whole world.
Those are exactly the same framing and the most likely outcome is left politicians saying, "why do you allow this 'sideloading' at all Google? I have a constitutent who got scammed, why did you allow it? Are you one of those awful libertarians? You should be more like Apple and review all software, otherwise you clearly aren't caring about consumer protection as much as Tim Cook does, up your standards or else we'll regulate you".