There is no age limit; the jpouch surgery has been performed on people in their 60s, 70s, and 80s. It's really determined by the health of the patient. People with multiple health problems may not be considered.
I also worry if chronic rectal inflammation will trash the tissue and muscles needed for a successful j-pouch. I have had ongoing proctitis now for about
6 months with (relatively smallish amounts of) pus and blood every day.