It will go down as a black mark for him, and* you *the reportee. It, even tho perfectly innocent and one time, could cost him (and you) a promotion.
Let me make this clear, we’re talking about a light shoulder touch, a wrist or hand touch, not a pussy or ass grab. Absolutely anything sexual or out of line should be reported. But many people have no issue at all with being lightly touched in a innocent and non-sexual manner, and in fact they appreciate it.