The gretchin are with 6" of the bastions containing the big meks. So he ends up with a decent cover save on them. Making them even more of a worthless target for FS.
I'm thinking my FS's are going in to his BW w/ 15 lootas, they are the most likely to take damage out of the group. I'll also probably get lots of scatter on the gretchin that way, given what I've seen of his deployment.