I read the posts on the single parents thread that did refer to tables at WDW buffets being cleared while a single parent was at the buffet or in the rest room with her children. I am not sure how or why it happened or how often it happened but according this thread it does happen. OP, if you are concerned, I would just use your printer, a stock card grade of paper and a disney clip art and say something to the effect that we are away from the table for a few minutes but will be returning to finish enjoying our meal....please do not clear our table yet. I really doubt you will need it but if makes you feel better.....it 's works
When we dine at Chief Mickey's, we always ask for and receive and pay for our meal early in the meal as sometimes if not, it can take forever to take care of it later.