Arm strength and dexterity could be an issue here. Does entrust his un bendable arm? Do u even use un bendable arm on your front rolls?
I recommend crawling, hand standing(assisted, progressive) to build up shoulder and arm strength and dexterity. Then get back to un bendable arm. Then get back to the roll
It sounds like you posit that the arms are supporting the weight of the body. Should not be necessary - and in fact trying to get newbies to forward roll via the advanced concept/technique/proficiency of unbendable arm is exactly how many of us ended up with AC shoulder separation injuries within the first few months of training.
Suggest you look back at this thread and check out Ellis Amdur's approach: breakfalls first, then rolls.
Personally, I wished I'd had been taught falling by a judo person rather than the standard aikido way.