Although I still have my gallbladder due to liver flushing, enemas including coffee enemas, I would think that it can only be beneficial !
Without a gallbladder bile only drips slowly from the liver , which makes it hard to digest food properly.
The coffee enema stimulates the liver to help bile flow, which could only be beneficial !
But maybe someone who is in your position may come along and let you know their opinion!

Thank you JustinL for taking the time to reply and you were correct. I have just received a message from Gar Hildebrand who runs the Gerson organization and this is his reply for anyone interested:
Cholecystectomy does not contraindicate coffee enemas at all. To put this in context, removal of the gall bladder deprives the liver of its depot for storage of preused bile, ie., bile that has been partially saturated with toxins is dessicated and stored for additional uses. Bile goes through this process 9 - 10 times before it becomes too saturated with adsorbed solutes and is allowed to work its way out of the body through the intestinal tract. Post-cholecystectomy, the liver compensates for the lack of stored bile by producing more, which it is quite capable of doing. Many people find that grazing with 6 small meals per day will help them avoid digestive problems.

On challenge with coffee per rectum, the liver and small-gut wall intensify their detoxification enzyme (glutathione-S-transferase) activity six to seven fold. Bile production itself is increased by as much as 25% - 30%. Once the palmitates of the coffee have been cleared, bile production returns to normal, a process taking 30 - 60 minutes. Detoxification enzyme activity remains elevated for hours