It's opt in, anyone that wants to accept zero conf can just insist that all transactions don't opt in.

>a long standing problem with the simple solution

Hard forking bitcoin is not simple. It's never been done before on purpose, and many people are extremely hesitant to mess around with a billion dollar system.

Why is it hypocritical? He complains that some transactions took too long to go through. With RBF, those transactions could simply be resent with a higher fee. But if you're against RBF, then you need the original transaction to go through, and you'll have to wait if it had a low fee.

Basically, the problem is caused by his own opposition to RBF, as far as I see.

(Disclaimer: I've been spending less time around the bitcoin community recently, so my information might be out of date. The patch that was committed is definitely opt-in, but I can't guarantee all the mechanics work how I'm describing them.)