This is horrible and a symptom of the sickness and toxicity in some elements of our 'society'. What else can one say?
Almost certainly, from the description of the incident, it was a passenger in the vehicle who perpetrated this assault (unless - most improbable - it was a LHD vehicle). This figures. There is a kind of gang instinct that prompts idiots to get together and concoct this sort of outrage. It is never a 'spur of the moment' thing, it has to be a conspiracy between the driver - opting to drive dangerously close to the cyclist - and the passenger - preparing to shove.
I have had three incidents of this type happen to me, now. Only one of them, the first one, was the only one to unseat me. It happened back in 1982, but I remember quite clearly. A small white van passed me on a country road, I ended up on the verge and in the hedge, scratched but not badly hurt. Reported to the police but without a description there was nothing they could do.
The second, in 2005, was a punch on the ear. Didn't injure me. The passenger admitted to being drunk. That time, I got a registration number, phoned the police, and in due course they caught up with the offender and cautioned him.
The third was merely a gentle push on the bum - but I reported that on this forum only a week or two ago. The driver is known to the police but they can't do anything unless he identifies his passenger - which he won't. Apparently even that push is classified as 'assault'. I would like to nail the driver for careless/dangerous driving, but the police need corroborative evidence for that.
Back to this unfortunate victim in Manchester. I really hope, not only that he makes a full recovery, but that he isn't put off cycling! Even at age 73 he may have many years in the saddle still before him. Remember these incidents are still relatively rare - I have spoken of three in over 50 years of cycling!
