Well, we first need Video proof that they did it, then we can sing the praises
Can't you just check ladders on PTR? I can't start the game for the next few hours, but it should be possible for anyone to see their classes, and unless they've already purposely changed it even their specs and gear as well.
But OP said "watch the final round" so I guess there's a video somewhere... I sure hope so ;-)
Just being there doesn't mean much, since there is no way to know if they used an Exploit or not. If it's 100 lvls using an Invulnerable Exploit or something, it's has good has nothing.
If you mean "invulnerable exploit" like beacon sail, I inspect that party, they are 1 Monk, 1 Barb, 1 Crusader, all zDPS with millions thoughness and gear "working as intended"
I love how your first post is a "working as intended" Blizzard bash on a topic that got Blizzard's attention and is going to be fixed now.