Oh dear, that's a real bird brain lol. Cats hunt and kill pigeons so it's clear that this one didn't have that in mind or the pidgeon would have had it.
I think the pidgeon just wanted to nest on something warm, bless.
Looking at it again, I think I know what triggered the cat: pigeons have sharp claws which I think it inadvertently stuck in the cat's eye. You can imagine just how much that must have hurt so no wonder the cat was so pissed about it. I hope the cat wasn't injured.
The unbelievable thing in this clip is not so much the feline's behaviour, but the bird's!
It is obviously a male pigeon doing his courting routine....to a cat??? All this cooing and bowing not to a lady pigeon but to his nemesis the cat? Unbelievable.
Yes, birdie's sharp little claw probably did get the cat in the eye, but even after the cat had (mildly) retaliated, pigeon didn't get the message; he seemed to continue his courting.
In fact, it looked like the fed-up kitty got up and turned away from the amorous avian, but annoyingly the clip stops dead just when the action continues, so frustrating.