He took Grandfather, though that was a different situation. I'd say this choice will probably be a big factor in if he can take lives.
A) too early to vote dude.
B) our friend doesn't really exist any more and would be going to Providence, who are not exactly going to keep him in a good situation.
C) no one had to deliberately infect him??? I have no idea where you're getting that. Nanites are everywhere, they're in the food, in the water, and in the food. Even of the people that could force nanites events I don't think any can do so remotely and only Father and Spankulot were in there. This was almost certainly just something that happened.
Edit:
And I have no idea where this came from either. Im fairly sure the QMs have said nothing to this effect, this was just something that was gonna happen and this was our last chance to see him before it happened.