Quite possibly.
Equally possible is that the riders were riding 3 abreast the driver gave a little toot to say he was there.
Got a volley of abuse while the outside rider stayed where he was in the road, to 'teach him a lesson'.
Do either things warrant being run off the road, of course not.
But in the video did the rider do everything possible to keep himself safe?
No, no he didn't.
Solely from the clip you can see, do you think it likely that the driver in question, saw the group in the distance, eased of his accelerator to keep a safe distance, and gave a gentle, friendly toot to warn them of his presence?
I'm quite happy to pass judgment that the driver is a moron, solely from the clip available. Especially so given that he chose to act in such a manner in a liveried company vehicle.