Honestly, I'm strongly reminded of 4e's shardmind art here, just more buff. I guess there's only that many ways to draw crystalline psionic humanoids.
Like golems, psion-killers are highly defensive, magic-immune constructs. Like golems, they a large number of HD (15, to be precise), DR/adamantine, natural magic immunity, a lot of natural armor, good strength, bad other stats, and a quirky supernatural ability (in their case, 1/round area Dispel Psionics).
Also like golems, they pretty unambiguously deserve -0 LA. Ignoring the fact that the party psion can just make one of these if it's that necessary (which they shouldn't, but still), it's very underwhelming even for a beatstick.