I'm pretty sure Penrose won't accept his own theory if it's only nonfalsifiable. At the moment, it's only an idea but if it is unprovable he'll abandon it or be very clear about its non-scientific status.

He's not a second Josephson.

I've watched enough interviews with Penrose to know you're correct. He likes all sorts of ideas, but he only really gets excited about the ones where he can see an experimental route to confirmation.

> it's fringe because it's almost certainly nonfalsifiable

That can't be true; those are two completely unrelated concepts. Compare "we're living in a simulation", which became mainstream despite the fact that (1) it is even more unfalsifiable than this is; and (2) it is identical in every way to the old, no-longer-interesting concept of "you are a brain in a jar".

I would consider “we’re living in a simulation” to be fringe. And that anyone who claims with any certainty that we are living in a simulation is a crackpot.

Speculating that we might be living in a simulation is of course all in good fun.

An idea being popular does not mean it is not fringe. Otherwise any sci-fi trope from the Matrix or Interstellar could be called “mainstream”. A large number of people also need to believe it is true with a high degree of conviction.

Based on a previous talk [1] there was a claim that you should be able to see events from previous aeons in the background microwave radiation.

In particular rings caused by the collision of black holes.

And from his talk he had reached out to colleagues from around the world to see if they did exist. So it seems like he does care about it being provable.

[1] https://www.youtube.com/watch?v=ftjwnjR0apY