It's legitimate. Aldon Smith, albeit a different player coming out of college, had 20 reps. Smith had 35 3/8" arms, and Clowney's at 34 1/2". Whether guys who knock Clowney want to acknowledge it or not, there is a correlation. For every Mario Williams who puts up 35 reps, there's a Von Miller who put up 20 - 21.
I'm looking at who runs the faster 40 tomorrow between Gilbert and Dennard, though. I'll bank on Dennard running in the mid 4.3's to low 4.4's. Gilbert might be a hair faster than that.