Drunk Driver’s Insurance Says They Won’t Pay Because He Was Drunk

To preface this, my father-in-law is working with an attorney, I’m just trying to make sense of how this is all working.

My father-in-law was recently hit by a drunk driver, rolling a couple times and totaling his car. He’s ok medically, though he’s beyond sore and was told to go to PT. The drunk driver’s insurance told my father-in-laws lawyer that they have a clause stating if their client was drunk during an accident, they don’t cover a thing for anyone involved. Is the insurance company really off so easy? I’m guessing my father-in-law could sue the other driver directly, but I’m not sure how that would play out.