The problem with using rectal meds only for UC is that of the old Step Up therapy treatment. This was an archaic way of dealing with UC particularly for moderate to severe cases where the patient got sicker and sicker before they were finally exposed to more aggressive therapies. Perhaps this escalation ties in with how your UC worsened TAA. Nowadays patients really need to be on a treat to target and top down approach where more aggressive therapies are given at the start to alter the natural course of the disease.
Rectal meds have some role to play but only a very limited way in the modern approach to severe disease. In fact mesalamine is now thought not to have any significant effect on CD.
I wish I had of had this advice early on. Maybe I could of saved myself from entyvio