Legal charges would be very unlikely to work, but it seems to me that recruiting Sophia to the wards would be something that would make no sense. Armsmaster may not be a telepath, but he does have a tinkertech lie detector thats basically just as good.
All thats needed is for him to ask Sophia: "Did you shoot a lethal bolt towards Taylor Herbert". It might not be acceptable in court, but it will certainly be acceptable in PRT where tinkertech is better understood/accepted. Would make no sense for Piggot to recruit Sophia after that.
Skitter KILLED THREE PEOPLE to the PRT's knowledge when they struck the deal to put her in the Wards, all three of them high ranking PRT/Protectorate personnel.
That's not counting Aster, or her multiple other cases of assault, kidnapping and whatnot.
Will they induct her into the BB Wards? Almost certainly not, for a variety of reasons.
Will she be
coerced inducted to the Wards anyway, in another city, under some sort of probation deal? Almost certainly yes.
People tend to forget that one of the PRT's core objectives is keeping the public safe, not justice, and they are perpetually strapped for personnel; if this can be achieved by simply co-opting amenable parahumans, cool.
Even those that have broken the law.
Especially when it is possible that said person is salvageable, like with minors; a Ward Sophia is still a Sophia not working for the Merchants or Coil, for example.
Think of it like how old-time judges used to give criminals they thought were salvageable the option of going into the military instead, for discipline and structure, in the hope that they will reform.