As previously reported, Trevor Cole, 44, of Tremorelands Farm, Cardinham put 52-year-old Rupert Hanbury-Tenison into a headlock and punched him as they grappled on the ground.
The victim, Rupert, is the son of the explorer and former chief executive of the Countryside Alliance Robin Hanbury-Tenison.
He said he was 'genuinely in fear for my life' and that he would have suffered serious injuries had he not been able to restrain him.
Mr Cole changed a not guilty plea to guilty this week on a charge of assaulting a man occasioning him actual bodily harm on June 4, 2021, when he appeared before Bodmin magistrates on March 10.
He was made subject to a community order and must undertake rehabilitation activities. He was fined £467, and ordered to pay £250 compensation, a £95 victim surcharge, and £660 costs.