User blog comment:Miskos3/Fairy Tail Chapter 368: The Third Seal, Review/@comment-5303512-20140124124804/@comment-7418318-20140124125803

Sayla told Elfman to install the Lacrima, not detonate it.

My guess is that it's remote detonated by Sayla herself, at the time of her choosing.

Maybe a change for Happy to repeat his bomb-disposal, but this time die for real. That could explain why his role was suddenly made more important. His last blaze of glory! Probably not, but we can hope.