Because this was an even better example of casuals being BTFO than Superman vs Goku.
Alien X fags knew nothing about post-gauntlet Hal. They knew nothing about what he did as Parallax. They knew nothing about how modern Hal BEAT that version of himself and then a Sinestro version of his Parallax self. They knew nothing about how he enslaved Nekron. They knew nothing about how he beat General Zod. They knew nothing about God of Light Hal or Black Lantern Hal. They knew nothing about about his pre-crisis feats. They knew nothing about Mandrakk or surviving erasure in a multiverse sized black hole dragging everything to non-existence within a hell that was Darkseid.
They knew NOTHING about Hal. In the bloopers "boomstick" has a LOL WTF? moment when he's told Hal is going to win because he, like the Benfagots, only knows Green Lantern as the black guy on the Justice League cartoon that shot lasers.
The Alien X fags hemmed and hawed about death battle doing something with Ben because they wanted people to be impressed by their shiny starman action figure. Then the big day comes and several decades worth of power flexing is dropped on them in minutes and they don't know how to take it.
It doesn't help that Death Battle underplayed the fuck out of Hal in their analysis. They described Zero Hour as "planets falling" which tells you everything.
Next time you want to fight a DC character READ THEIR FUCKING BOOK beforehand.