Technically, it's well within the rules to sign up and not play until 11 hours later.
Whining about it on the forums isn't going to change anything, and if anything, waiting 12 hours for the tourny to finish is much better than it was when there was a 24 hour time limit.
And I suspect that some people do it so that they can be grouped in a RG with "lesser" competition, and since it's well within the rules of the game to do so, I have no issues with people who do so.