Yes, it is true that it does depend largely on your own individual tolerances. The same holds true for tolerance of an ileostomy. But, the fact is that you have lived with the ostomy, so that is a known factor. It seems that you are also living with bathroom issues too, since you need the proctectomy now.
The other factor is your overall health and fitness. Are you a "young" 80-something, very active, fit, and motivated, or more of an "old" 80-something, with a history of difficult surgical recoveries, heart disease, diabetes, etc.? Or are you sort of in-between? Lots to consider, because some 80 year olds are better equipped to deal with probable early difficulties than some 50 year olds. This is why there is no clear cut answer. Only you and your family know what you are up to handling and what you are not.
I am going to pose another wrinkle because a total proctectomy is no easy surgery either, as many here have said the perineal wound was much worse to deal with than the j-pouch. But, I would hope that j-pouch removal is more difficult than proctectomy because of the scar tissue involved. Still, you cannot assume it will be a simple, easy procedure. Adding to the difficulty is the fact you had an intra-abdominal abscess, which would definitely have increased the amount of adhesions (internal scar tissue) that you have. This actually might complicate a j-pouch procedure too.
If you are motivated to have the j-pouch, I would urge you to seek a second surgical opinion (outside of your current surgeon's group). This might help you get some perspective. I personally worry about surgeons who do not fully satisfy their patient's inquiries. They may be fabulous surgeons, but if they cannot communicate, it can be a real problem down the road if there are complications.
Good luck,
Jan