Yes, it does. The SRD is wrong. (Well, the "2" part of "2 slams" is in the wrong column.) MM, page 97, confirms two slams for 2d10+11/19-20x2.
So this isn't a sole natural attack after all. No 1.5x Str bonus for you, Mr. E.
Even with two slam attacks, he's much better off with that spiked...