Unit tests aren't a TDD only thing. His complaint was against TDD rather than unit tests.
However he has a point. A bad developer writing unit tests is pointless. If he writes bad code why on earth would anyone think he'd write good tests?
Moon pig uses TDD, C.I. and all those cool buzzwords and look how safe their api turned out.
Relying on the code writer to test his own code is just about pointless.