ECDSA is almost universally used. It's deeply suboptimal in a variety of ways. But that's because it was designed in the 1990s, not because it's backdoored. This isn't a new line of argumentation for Bernstein; he has also implied that AES is Rijndael specifically because it was so commonly implemented with secret-dependent lookups (S-boxes, in the parlance); he's counting on a lay audience not knowing the distinction between an engineering principle mostly unknown at the time something was designed, and a literal backdoor.

What's annoying is that he's usually right, and sometimes even right in important new ways. But he runs the ball way past the end zone. Almost everybody in the field agrees with the core things he's saying, but almost nobody wants to get on board with his wild-eyed theories of how the suboptimal status quo is actually a product of the Lizard People.