Hm. Even though I don't like any version of a story wherein some fucking idiot on the spaceship is experiencing major, behavior-altering qualms about the thing they've always known they were doing...
...off the top of my head, I guess I would prefer to have that story take place among a crew of ostensibly sane people on one spaceship, as opposed to involving a second fucking spaceship and an insane sunburn monster.
But doesn't make sense that the man basically had a breakdown? There is def a sense of otherworldly things going on.
Not only have I listened to your commentary, I also have listened to both the directors commentary and the physicist's commentary several times over the years(Sunshine is one my favs). They basically say that the man has
gone insane. the secondary comm. track with the Professor guy does a better job of explaining the ending. It's been awhile now, so I wouldn't want to mince their words, but I think that if you wanted to rewatch the movie listening to audio track 3(I think), any of you would enjoy the hell out of it, IMO.