I do agree that it's probably best to hang onto him in deeper leagues until the final outcome is known, although I personally wasn't willing to take the risk any longer given what I've seen. I could absolutely be wrong and end up regretting it, but Dr. Andrews is what did it for me.
This is only speculation on my part, but the first major red flag was his tantrum after getting pulled last week. To me, that indicates a stubborn player refusing to admit he's injured. Hell, I did the same thing back when I was wrestling in college, and ended up having to get my neck fused as a result. My gut feeling is that Burnett is trying to downplay something serious because he can't believe it's happening to him again. I feel extremely bad for him, and hope that he can resume his career without further injury. He really is a very good pitcher when healthy.