I would
(a) cordially explain the law to the cyclist and why what he is doing is dangerous

(b) if he continues his unsafe behavior - unsafe to him, you and every other cyclist he encounters - I'd give the cops a heads up and see if they could respond to the unsafe situation and explain the law to the guy.

Sure he's behaving that way because of his accident, but he's being unsafe to himself and others. Nobody has the right to break the traffic laws for their own sense of security when it endangers others.