Earlier quoted context omitted.
If you accept that (1) there is a substantial amount of mal-content that Google should censor, and (2) a key use case for federated messaging platforms is to evade censorship, and that (3) client applications can be functionally part of a federated messaging platform while legally separate from it, then those client applications are fair game to be censored when they deliver mal-content. Now I may disagree with parts…
That would presumably include Chrome and https and enabling use through VPNs? The above are use daily for extremist content, CP, circumventing numerous national laws in numerous places... Hard to draw the line.
If you run a monolithic, centralized service specifically designed to avoid censorship, and you don't moderate what users do on your service, and some of those users hurt people with your service, then you should expect your service will be shut down as Parler was.
And if you do the same thing, but separate the front end from the back end, and have different entities run them to provide legal separation, while practically and functionally the result is identical to that of the monolithic centralized service and your system is used to hurt people, then you should also expect that whatever components can be deplatformed will be deplatformed.