I disagree. What you do (well, and what I do in my code) is this: You cache the original IP packets containing the Client Hello. You inspect those packets. And you make your DDoS protection etc based on this. And if you decide the packet is OK forwarding, only then you replay the original IP packets to the destination.

I know that you can not inspect content this way. But there simply are situations where content SHOULD NOT be inspected.