I had a similar experience here in Baltimore. I offered a guy help who was walking his bike on the sidewalk. It was an impoverished neighborhood, and a rusty bike, but I had the patch kit and a pump.
He barked at me, "NO". Okay, fine, just thought I'd offer, maybe he didn't have far to go, (unlike your guy), but I think a polite no thanks I already called someone who's meeting me, or I only have a block to go would be better, but a lot of "serious" roadies are anal retentive anal pores, not all, but a lot.

The dude I tried to help was not a "serious" cyclist, he looked like he used his bike for transportation out of necessity, so maybe he's sensitive about others touching it. But if your dude was really a "serious" cyclist and riding that far, he should have been prepaired to fix it himself, or accept help politely.