Is the Fake!Cap in question the one who will later become "US Agent", because I've been reading the two volumes of Operation: Galactic Storm (with difficulty because I don't care about most of the comic crossover), and it seem to me that US Agent's superpower is being an asshole who is very good at pissing people off. That jerkass joked that he voted for Mockingbird to be on the team, because at least she's easy on the eye...and then he insulted She-Hulk's waistline.

Come to think of it, from one of the first issue of the Ultimates I came across, the one where Ult!Cap is a jerkass who told the Scarlet Witch she should cover up more in a "stop dressing like a slut" kinda way (as oppose to, "Wanda, aren't you cold right now?" *concerned* way), is Ult!Cap actually US Agent as opposed to Steve Rogers?