There is nothing, technically, that he can do to prevent third party clients. That's the same thing we did in the times of ICQ, AOL and MSN Messenger.
And there is an actual demand for features not provided by the official client, as stated by the amount of PRs contributed by non-Signal developers waiting in their GitHub repo, so people will continue to come with their own changes.
> There is nothing, technically, that he can do to prevent third party clients.
There are plenty of technical ways of detecting and blocking 3rd party clients (using both in-channel and side-channel, uh, signals); the only challenge is that it becomes a never-ending arms-race
And there is an actual demand for features not provided by the official client, as stated by the amount of PRs contributed by non-Signal developers waiting in their GitHub repo, so people will continue to come with their own changes.