Yeah, regardless of the moral implications of it being arguably a good thing she was stopping literal biological warfare from happening, I am pretty sure the way it was portrayed in the episode and the fact Burns was most likely going to sell it to the government or something (I don't recall for certain, and Burns WOULD unironically make biological warfare stuff just for the lolz, but pretty sure this is the case) would get this labelled as straight up domestic terrorism. XD
Soooo.. that (and the aforementioned crossing several state line factor) probably would need a presidential level pardon to get Mona to not be a wanted criminal anymore
... Though in all fairness, with how crazy the US is crime wise nowadays, Mona isn't actually being ACTIVELY pursued due to having bigger fish to fry, it's just if someone recognizes her or she goes to a less chaotic pocket of the US, at the very least an attempt to arrest her would be made