Seems like he only got 20 feet further ahead before being stuck behind a car, did he honk them too? almost certainly not.
Its just run of the mill vehicle aggression towards cyclists. and technically illegal, you could report him to the police, and he might get spoken to(*probably not*). that might make him think twice before being a ******** next time. probably wont though many many ordinarily nice people transform into *********s when they get behind a wheel. its a culture issue.
Being hooted at for simply being on the road, does seem to be quite rare thankfully. I wonder whether in some driver’s minds, when they happen to see a cyclist on any kind of path (including footpaths), they think ‘that’s where you should be – off the road’, and then bank that thought for future use when they have to wait for 5 seconds.