Clearly he had undergone a 9mm brain operation due to Contessa shenanigans.
Yeah, I don't know how that would work, either.
I just can't see any other way for someone to remove a tinker-tech bomb placed inside their very brain, on their own, with no advanced/precise tools, and with the only superpower in their grasp being the ability to split timelines.
Even if your skull hasn't been sealed, if you actually think you can just grab it, open it, grab the tinker-tech bomb and pull it out of your own brain with absolutely no help, technology or a professional and experienced surgeon directing you, even if you were to keep loading the Quick Save every time you fail, it'd take you a long, long time to get it so perfectly and precisely that no further damage is done.
Either that, or Coil got a second-trigger and got a PtV expie.
Which is even worse.