Well, it's not likely to be a colorectal cancer, since these occurs after 50. But it could be some other non-harmless tumor, like hemangioma. It could also be intestinal hernia, the location is a bit unusual though.
It could also be a localised bleeding. If he feels well, I think he can safely wait for the doctor appointment.
Writing off the possibility of colo-rectal cancer due to a person being below 50 is a huge mistake. Many people, particularly those in certain industrial occupations (such as firefighters in particular) have a marked incidence of colon cancer well below that age range. It is a colossal mistake for anyone to assume that simply being under 50 is some kind of guarantee.
Can I ask please what the diagnosis was please in the end? This is identical to my husbands situation at the moment.