'Superhero' is still an incredibly vague term, and Magnus hasn't quite sorted out the implications of it yet in relation to human culture. It isn't as if they have anything similar on Cybertron. But from what he's seen they are generally trusted to handle dangerous situations, it probably wouldn't be unreasonable to allow Steven to stay.

"Very well, but you need to inform Alpha Force of your present location and remain in the work area designated for CONDOR's human agents unless you are being supervised by one of the Autobots."