This is why wait-free and lock-free are separate concepts. Author is not claiming wait-free.

Obstruction-free, lock-free, and wait-free are increasingly strong guarantees for non-blocking synchronization mechanisms. A sequence lock is a blocking synchronization mechanism and therefore provides none of the aforementioned guarantees.

No, it's neither wait-free nor lock-free. Wait-free guarantees all threads make progress, lock free guarantees at least one thread makes progress even if another thread is suspended or dead.