Hayden can't possibly be stupid enough as to think he can fake a stroke to avoid giving testimony or being prosecuted. There is no way he could convince doctors of that if it didn't happen. I think this is more likely, and he knows time is almost out:
"Dec. 13, 2004 - Anger and other negative emotions may trigger stroke, research shows…Negative emotions were the most common possible trigger. Positive emotions, in contrast, had no effect. "It is possible that negative emotions evoke more intense reactions," say the researchers. There was a 14-fold increase in stroke risk with both negative emotions and anger."
webmd.com/balance/news/20041213/anger-guilt-may-trigger-stroke