> Isn't this conflating encryption with trust?

Absolutely, and the claim is somewhere between nonsense and pedantry bordering on nonsense.

The exact same thing is true for, say, Signal. The provider delivers the client, and they aggressively block non-official clients from participating. So the “ends” in end-to-end are ultimately controlled by Signal. But as long as you trust the Signal company not to insert a backdoor into your client, it’s still true that the company can’t read your texts.