Pound for pound means best per pound of weight basically. Remember, that Volk moved up, just because he lost doesn't actually make Islam the number one pound for pound. I would agree with the reasoning that Volk is still the pound for pound champ. He basically moved up, and nearly won. That's the very definition in my opinion.
Well I don't agree with that reasoning and nobody forced him to go division up, but same thing happened with Adesanya when he tried that and I think Adesanya is better fighter than Volkanovski pound for pound.
If UFC can make tricks like moving up Jon Jones in that ranking without any fights, than I can create my own Notblox ranking and put Khabib as still best pound for pound fighter in MMA
Obviously, to really cement things I think we'll need the rematch. It was just too close to call. I also, don't take Islam as much as a family man as Khabib. I might be wrong in that, but Khabib left at a time where he was dominant. I don't see Islam being quite as dominant at the moment. That could change, obviously.
I do agree with you that we need rematch Volk vs Islam, but I see now Islam is already asking for his next opponent, that means mother, Volk and retirement will have to wait