I've considered this myself
I suspect that Hellmuth's emotions are mostly real, but that a lot of it is exaggerated for the tv ratings, for popularizing poker by making it interesting and finally as a ploy to get other players at the table to try and "exploit" Hellmuth's "pseudo-tilt."
Hellmuth's style is typically a tighter/nitty style, so what better way to all of a sudden get action than to "tilt" (I think some is an act but some of the emotions real too) and next thing you know, players are calling him down or being set up.
The more I learn about poker, the more I realize that Hellmuth's line of thinking is often times correct. I can see how frustrating it can be when you are playing less
hands (tighter/nitty playstyle) and then you lose the pot to someone calling your raise with QT or Negreanu messing with you by winning with 72o. I think a lot of Hellmuth's emotions are real, but the "tilt" is largely an act. Not 100% fake, but not 100% real and certainly under awareness of "how much" Hellmuth "lets out" in his ranting.