Any time I've ever left a job because of a project, all that time spent working on a broken product has left me with tons of time to figure out how I would do it on my own.
The guy's framework existed before he joined Angular, he announced that they were merging, and then he changed his mind. Your analogy doesn't quite fit.
I'm skeptical of several things, but so far trusting that team has gone well for me.
I'm skeptical of several things, but so far trusting that team has gone well for me.