Uc was just an example but nevertheless the UC can be used to kill infantry, just as raketen can be used to kill LVs. And as you pointed out you have to fall back, and thus losing map control, when you don't want to get your troops wiped(or bleed too much).
UC can't really wipe infantry unless you mess up and if you do it's on you not the UC. You have to pick your fights, retreat if needed not to suffer any bleed. Just avoid it or lure it into Sturms+volks in green cover or into raketen. And you have to get a raketen. Even if it just damages UC 1)he has retreat and spend muni to repair delaying Vickers or flamethrower and making him more cautious winnig time for you 2) or he has to repair with sappers losing map presence for 2 units, either way it's a win-win situation because you can safely cap with raketen and it stays relavant all game long anyway.
OKW player that doesn't use raketen vs UC or clown cars in 99% cases pays dearly for that. Don't be greedy. And after you get fausts UC is not that big of a problem.