Good of you to notice this guy had a center light out. Hopefully he is a member, or someone who is a member knows he/she, and informs them.
I used to honk at folks in this situation, and try to tell them about it, but these days they get angry and shoot at you!
My favorites are the ones that run down the road for miles with their turn signals on, never changing lanes.
It is better to keep your mouth closed and let people think you are a fool than to open it and remove all doubt.