I don't care how well trained he is. Has your dog ever wagged his tail? Because a tail wag can break a chin's ribs. Also the fact that you said he is a hunting dog sent up a major red flag. Hunting dogs have instincts, and no matter how well you train them, the instinct can kick in without any warning. Not to mention there are tons of diseases that dogs can pass on to chins without any warning sign whatsoever. Ferrets are different, because they are also predator animals. Chins are strictly prey in nature.
I understand that you've heard differently from your breeder and other owners, but I urge you to trust the users on this forum more than anyone. Some people on here have been breeding chins for 50+ years. These users have made every mistake imaginable and have the horror stories to tell, so please, learn from their stories and not from your own.
Chins that young should not be having play time. Your breeder is mistaken. When a chin is that young, all their energy and calories need to be saved for growing, and playtime burns them off. You can still have great bonding time with your chin inside the cage until they are old enough to come out.