Lots of nuances that make me assign 70% probability (as opposed to, say, 99% if a physical law prevented it):
Conventional superconductivity is right out; the mechanism is well-enough understood to claim that’s most likely impossible (here I actually would assign ~99% probability);
Unconventional superconductivity is not that well understood, but generally speaking you need a very specific electronic structure. The cuprates, for example, have been tuned extensively and only get roughly half-way to room temperature;
High-pressure hydrides might well reach superconductivity at or above room temperature, but require immense pressures which can only be reached under extreme conditions such as diamond anvil cells.
More importantly, theoretically modeling these ab initio is difficult, because density functional theory (tool of choice for electronic structure calculations) on its own can’t do it. Beyond that, you quickly run into problems. A guy in my lab spent an entire PhD developing a method for accurately predicting the ordinary electrical resistance (Ohm’s law) of a few simple materials from first principles.
If these don’t exist in our universe, then it doesn’t matter how intelligent your friend is. If they do exist, my claim is that finding them via ab initio simulation is significantly harder than designing quite complex viruses. Therefore “AI can design room-temperature ambient-pressure superconductors” does not provide a good warning signal for “AI can design complex viruses”.
For instance, I can guarantee you that your friend the superintelligent AI will not be able to calculate the full many-body wave function of some system of, say, 1000 electrons.