I wouldn't reallly be quick to criticize this as taking the piss. Beautiful Day and Vertigo are appropriate to get the crowd into it. We need that in every benefit gig.
HMTMKMKM is quite an odd selection though but perhaps what the original poster meant is that it is God talking to the beachgoers "I'll hold you, thrill you with all your beach Christmas fun, but I'll take you away and back to me." After all, natural disasters are God's doing as part of his bigger plan. And those whom he took away are already gifted with his kingdom and eternal life. There also is the lyric "they'll want their money back if you're alive at 33" and I'm pretty sure thousand of people younger than 33 died there.
Who's Gonna Ride Your Wild Horses does have the lyrics "who's gonna drown in your blue sea/ who's gonna taste your salt water kisses / who's gonna take the place of me." So maybe the original poster wanted these lyrics to be heard by a live audience.
Just as U2's beautiful song Yahweh says to God "take this mouth so quick to criticize", let us not be so quick to criticize the original poster. We should always view other people's posts and ideas with an open mind.
Finally, always bear in mind that U2 will be performing to an audience far away from the disaster so they can actually play any song they like and they won't take the piss. But knowing U2, they will be extra careful in their song selection and make it appropriate for the ocassion. And to be honest, I don't quite agree with MiggyD's song selection but I see where he is coming from.
Cheers,
J