I agree with mammo children do not make up this kind of thing, do not leave him with the child ,it is possible that the 9 year old has had this done to him ...
Listen to YOUR son, he's too young to make this up, and bubba is old enough to lie. I would not allow the two of them to be alone together any more. If this continues, and it will, it will scar your son for life. A nine year old will never admit to this and his parents need to look further into his behavior. Protect your son by keeping them apart, hurt feelings or not!