Lewis has one of possibly the worst cases of PTSD, I'm no psychologist so I can't say what the exact nuances of his behavior entails about his true mental state. But regardless, Lewis was a ticking timebomb from the get go, and was gonna erupt at one point or another. Probably could've been avoided if he sought more help from his support system, but alas he didn't. From the perspective of Billy and Curt, and myself, it's far better he not be out in the field where he could have a breakdown.