"... for a few miles," and, "I was never sure if he knew..."

If you'd made yourself known with a cheery word, and taken turns towing (assuming he'd been willing to ride as a pair) you might have made a new riding buddy. As it is, judging from his response and actions as you've described them, you simply spoiled his ride.

Some people enjoy riding in pairs or groups, but some of us go out on our bikes to get away from other people, think through things, or achieve personal goals.

I'm sure you meant no harm, and you're probably surprised and hurt by the responses to your post, but if that means you approach the situation differently next time, that's to the good.