Toilet training/loose bms

I have a daycare child approaching 2.5 yrs, and the parents want him to start toilet training. The problem is that he has about 2-3 runny poops a day. I've told them that I suspect he has a dairy allergy. It's gross enough with a diaper, so I can't imagine pullups or underwear. There are also some developmental delays(which mom and dad will not acknowledge) He's not ready. Maybe 6 months from now, but not now.
Have you ever refused to train a child based on the consistency of the bms. I've never had this issue before. Thoughts??

Does he show any signs that he's ready to train? If not, I'd be explaining to the parents why I'm hesitant to start. IMO, if they're not ready it just makes the process take longer and can be more detrimental than successful

The poops aren't a problem for a child ready to train. If they are aware of their body signals, can give you a heads up and can make it to the potty in time them whether they poop once or 4x a day loose or hard isn't an issue. What makes it an issue is if they are not ready and are pooping in their clothes.

If you don't think the child is ready I would express your concern with lack of signs he is ready. If they insist then make it clear you will give it a try after they do it full in on the weekend and if he has X number of accidents then you will abort until he shows signs of being ready. I wouldn't talk about the poop consistency as a reason he isn't ready. You CAN bring this up after a day of trying and sending home that really messy clothing. Just remove...put it in a large ziploc, seal and send home. They will quickly see the mess and hopefully rethink their position!

I not think the consistency of BM's good enough reason to deny request to train. I do think if he's not ready, that relevant. Some people have hard BM's, some soft, and normal changes per person. If your issue is cleaning the potty after his BM's, then train him directly on toilet but it seems wrong to deny training if this is the real issue.

I've said to parent that a child not ready and I have document detailing what I define as ready - child need be able to pull pants and underwear up and down independently, child need be able to follow instruction to go to toilet, child need be able communicate if need go. I've never denied based on consistency of BM being loose and less desireable.