Well, my previous post is moot now, I just saw the grey sleeve on Washburn's right arm. Oops.
In all my years of umpiring, I have never had anyone question sleeve length, only when pitchers would try white undershirt sleeves, which I have them remove.
You are right 1.11(c)(1) does not distinguish between uniform or undershirt. Apparently I misinterpreted that "sleeve" refered to the uni shirt.
Well, I kicked that one. Everybody pile on!