Ugh. The process in comics is as follows:
A. You live.
B. You die.
C. Your soul goes to the light. The afterlife. Heaven. Whatever the hell it is.
Something with Wolverine (be it magical, a remnant of his past, or something dealing with his mutation) let's him make a choice after B. and before C. Wolverine can go with D.
D. Return to the world of the living.
You see, it doesn't matter how much or how little of Wolverine's body remains. His immortality is not genetically related, it's supernatural. If you don't really like it, that's fine. But you can't STILL argue that Wolverine can die (and stay dead) from massive blood loss.
Could he still die from that? Sure. But he could come right back. You see, Wolverine isn't truly immortal in the sense that you can't kill him. He's immortal in the sense that IF you kill him, he can return to his body immediately.
Think Mr. Immortal, kind of. Deadpool decapitated him, yet, he was up and walking around on the next page. It wasn't really due to a healing factor, but rather, his mutation.
Similar with Wolverine.
Wolverine being Immortal is not PIS, even if you believe it to be stupid. It was simply a creative decision that the writers decided to make. They wanted to take Wolverine's character in this direction, who on this board has the authority to stop them? Hm?
Wolverine Stabbing Thanos (period. Much less with the infinity gauntlet), however, IS PIS. Thanos survived a Black Hole without so much as a bruise. He took blasts from Odin and still stood in defiance. He took a pretty powerful blast from Galactus, and still lived. He laughed in the face of the Surfer's blasts, and took shots from a Warrior Madness Thor without too much trouble.
Yet Wolverine could kill him? While wielding the INFINITY GAUNTLET?
No.
*shakes head*
But that's okay. Wolverine isn't as PIS-filled as a lot of people argue, he just is disliked by a majority here, so many of his feats are labelled as PIS.
And, hell, maybe some of them are, but no more than some of Spiderman's PIS feats, or Captain America's, or Daredevils.
The latter characters just aren't brought up as much, not to mention that the latter characters aren't half as annoying as some Wolverine fanboys.
Though Wolverine fanboys aren't half as annoying as Hulk fanboys.
Who aren't really quite as annoying as Storm fanboys.....