Diverticulitis patient: last time I had a hot dog (steamed) I ended up in er. Do u think a grilled hot dog will make me return to the er.

Coincidence? Hot dogs have not been specifically shown to trigger attacks of acute diverticulitis. They're not healthy, and I'm sure you can find something better to eat, but shouldn't trigger diverticulitis.
Hot dog. Hot dog may have coincided with the development of diverticulitis last time but was not the cause of it. Diverticulitis is known to be caused by bacteria in the guts. Unless you have some sort of allergy to hot dog, i would try it again.