[Callers] What to do with a really bad new dancer?

Hi everyone, Lately a new dancer has started coming to our dance and he is bad enough that he will often make the set break if the dance is moderately challenging. He seems to have some kind of impairment and walks very stiffly which means he will often not be on time for a figure and also often does not remember what is coming next. We want to be inclusive but at the same time his presence negatively impacts other dancers in his set and while some of the experienced dancers will take one for the team and dance with him, it is an unpleasant experience to be his partner. Unfortunately, we always have many new dancers and having one couple not be where they should be can really throw them off in some dances so I feel like I have to push and pull him around to be on time, despite the fact that it's a little rude. A recent caller to our dance called him a "speed bump" which was quite accurate. I'm sure other dances have had experience with similar troubles, does anyone have advice on how to deal with this so that other dancers still have a good time yet we are nice to this problematic dancer? Thank you Marie ContraMontreal