No, certainly not. I agree with you; the change from 2048 to 4096 isn't interesting.
The interesting part is that he 1) generated a new key (okay, not actually interesting in itself), 2) is using it in an isolated install, 3) this isolate install is on entirely separate hardware, not just a VM, 4) this separate hardware is new hardware that has never been networked.
Tinfoil Hat Linux was never really about using large PGP keys, you could use large PGP keys on a co-located RHEL box just as well as you could on an old crusty THL box covered with shoes and bluejeans in your closet. Rather, Tinfoil Hat Linux was about cautious (really, hyper-paranoid for the hell of it) treatment of private keys and plaintext. Extremely cautious treatment of plaintext and private keys is what he is currently going out of his way to do.
Is going to such an extreme (new hardware that has never been networked?) really necessary? I don't have the expertise to say. What I can say is that is nearing the sort of baseline paranoid treatment of private keys and plaintext that THL is known for. He's not blinking out leaked documents in morse code yet, he isn't worried about white vans down the street reconstructing the images on his monitor or RF leakage from his CPU giving them bits of his private key, but we are at the point where that is the next logical step.
(And no, aliens never landed at Roswell (or anywhere else), JFK was shot from the Book Depository (and only the Book Depository), and Stanley Kubrick did not film the moon landings (that was done with television cameras mounted on tripods, the LEM lander legs, and the astronauts' chests))