This is not about encryption, it’s about lack of cooperation with the authorities, and breaking French law as a French citizen.

It's at least https encrypted and stored encrypted on multiple telegram servers.

So technically telegram could provide that data.

I guess that's the angle.

Why? He seems to be happily providing information to KGB (sorry, FSB), russian security service or ignoring backdoors they already have. In fact, telegram is one of the most powerful disinformation tool employed by russia. None of sane and savvy person who stands up to autority would use telegram.