HDLG – Having been involved in a 4½ month court trial where things aren’t as black and white as your comment would indicate (if only they were, life would be so much simpler), there will be a lot of evidence that never gets out into the media/public domain that will show varying levels of mitigation for an individual(s) actions.
Having had that court experience it certain made me less inclined to jump to automatic conclusions of guilt or not based off of just the small percentage of information that news outlets reports on to Joe Public.
In no way shape or form do I condone what he did to that gentleman and there of course must be punishment for his actions but I am just not sure how much a prison sentence in this case will serve as it would appear so out of character for the man given what we know about him (calling the police instead in a subsequent incident that happened) and how he has got to where he is in his professional life and what he does in the community prior to this incident.
Had there been any kind of history with this type of behaviour then yes a prison term would be 100% warranted but maybe a suspended sentence with court mandated training and/or counselling for any underlying issues may have been a more constructive way to go. 
With regards to his business I hope some workaround can be found (does he have an assistant trainer that could step in?) for the next 18 months or so – it is not quite as simple as horses and staff just going to other yards and we all go on our merry way.