I wonder whether he might have been having some hygiene or stomach/intestinal issues — had the bean and burrito platter the night before? — and was afraid of consequences, but was unsure how to handle that up front? Kept the appointments because he didn’t want to disappoint (or lose the donation) but wasn’t up to full participation?
I’m speculating, I admit. And it would be a reason, though not an excuse. And a comment on how good communication is so important but not always easy.