While Peter Monro was loading the truck with his son Philip Monro, he noticed some damage to the fuel tank, and raised this with Mr Higgs, the authority said.
Mr Higgs said he did not know what happened, and assumed a loader at a port he had visited earlier that day must have caused the damage.
An altercation broke out between Philip Monro and Mr Higgs, after Philip Monro loudly loaded tools into the truck, the authority said.
Philip Monro said the noise "sparked Mr Higgs off" and he ran at him "full tilt" and shoulder charged him.
However, Mr Higgs told the authority that Philip Monro became aggressive and abusive, and felt his mood was "pretty dark".
Two days after the incident, Mr Higgs apologised to Philip Monro.
Mr Higgs said Philip Monro told him that while he accepted his apology, "his wife wanted Mr Higgs gone", and he was "lucky he was on angry pills or it would have been worse for him".
Mr Higgs told the authority he felt bullied by Philip Monro and was advised by his doctor to take time off.
When he was ready to return to work, he texted Peter Monro, who told him he didn't need to come in because the weather was bad.
Peter Monro told the authority he had not suspended Mr Higgs, and weather often impacted what work was available to his employees.
He then notified Mr Higgs of a meeting, and warned him that disciplinary action, or dismissal, could take place.
The authority said despite Mr Higgs' apologies, Peter Monro was concerned similar incidents could happen again, and following the meeting decided to terminate his employment.
Authority member Helen Doyle said while she was not satisfied Mr Higgs was unjustifiably suspended, she believed he was unjustifiably dismissed.
"Mr Higgs has a personal grievance that he was unjustifiably dismissed from his employment and is entitled to consideration of remedies."
Mr Higgs was awarded $2000 in compensation and $1199 in lost wages. Costs were reserved.
Neither party was immediately available for comment.
