Your title said "riding buddy". If it was my riding buddy I'd know if he was like A) the fellow to the north of me who can and does ride 24 and 34 year old bikes wherever he wants and gets there and back, or B) the fellow to the west who has a malfunction (if not an actual breakdown) going around the block then fixes it with Gorilla tape because it's better than duct tape.
Even if I went on a trip with B, I'd have to stick with him to the best of my ability, but that doesn't mean I'd babysit while waiting for parts.
You seem to have been not with a buddy, but a new acquaintance. You didn't leave him in particular danger.
If anyone should feel awkward about the situation (as you've presented it) it's not you.