Originally posted by Juntai
I mean if we’re ignoring the fact that he was nearly powerless from red sun from the Sun Eater and that the explosion was 50 supernova worth of Entropy explosion, and not solar energy, then sure.
It's been some time since I read the story but you're correct, he was blasted by red solar radiation in the previous scene. So I'll retract that point since it's not necessarily reliable.
Let's look at another example.
Action Comics #867
Here Superman is knocked unconscious by a Sun-like star supernova after Braniac triggered it. He was at a inhabited planet at the time, with earth-like buildings, so it's fair to assume the conditions are similar to that of the Earth and the Sun, i.e. a distance of one astronomic unit, meaning that very little of the energy actually reached him. We could speculate further by pointing out that it was a yellow star (which Superman gets his powers from) so it should have even less of an effect, but I think that's unfair/reaching.
Surfer is a lot closer, and unaffected.
Silver Surfer (1987) #145
So here you have a phenomenon that knocks out Superman but leaves the Surfer unfazed. And as far as I know, Clark has never tanked a supernova, let alone remain unperturbed by it like the Silver Surfer.