Hmmm…Pretty sure Steel’s cybernetics are exposed for the most part, so assuming we don’t get knocked around to much and have enough time (i.e. a subtle MC capable of playing cat and mouse long enough) the nanovores might be able to ruin his armor and make it unusable. An MC with enough control might even be able to seep past the armor (exactly how tiny is a nanovore?) and would be able to eat straight into Steel’s cybernetics. I’m not sure exactly how dependant Steel is on his mods but it’d at least play havoc with his fighting ability. Either way anyone who’s boosted is going to have major issues with a competent enough MC without them ever having to use telepathy directly on them. A tech savvy MC might get away with that more easily, too, passing off their control over the nanovores as technological prowess.
I do agree that telepathy isn’t the most subtle enhancement ever but there are still ways a sneaky enough MC could pull it off to great effect while still maintaining anonymity.