Sorry but, why in the fucking hell would this Harry go to number 4, attack or no attack??? Why in the FUCKING HELL would he even consider it?
He still has number 12 to stay in, or at Hogwarts, so I'd have said a great big FUCK NO to ANY ridiculous notion of EVER going back to number 4. That was something Albus wanted and remember, they learned Albus was a great big traitorous piece of shit.