Doesn't matter; it could be that we now have an uncontrolled vector for the spread of the infecting nanomachines. How will Alice manage to deal with that?
Yes, we're going to find out
real quick now whether or not the power is viral.
As for the limits of the power itself... Gavia says nanobots need a guiding intelligence, but they're obviously capable of interpreting directives like hand motions or possibly the thought of their user; she makes fireballs, lights, and slices up her apple without any obvious commands. Ardent may be carrying a strain that interprets his desire to be helpful and uses his mental image of what the target object
should do to guide their modifications.
If I were Alice, I would next present him with a device sufficiently complicated to activate the 'bots, but that Ardent doesn't know the function of. Maybe something like a phonograph or a mechanical calculator. Or blindfold him, and see if the power still works on things even if he doesn't know what they are.
If it doesn't work in those situations, that means Ardent's strain is a tool that reads his intentions. It would also mean the ability probably isn't viral, since the Nice Birb isn't likely to know what other devices are supposed to do. However, if it
does work in those cases, that means the 'bots themselves are AI-powered (and Gavia was misinformed by the Praeses about the nature of nanotech).