McIntyre had concerns over Mr A's behaviour and sought to have him dismissed on several occasions, the court heard.
The authority heard how McIntyre told FNS director Peter McGilp that he had been told by Marino that he saw Mr A at a local meth house – something Marino denied saying to McIntyre.
McIntyre alleged he received a threatening phone call from Mr A following this incident.
A week later Mr A was arrested for assaulting a member of the public. McIntyre told McGilp he had received abuse messages from Mr A.
McGilp, who has since passed away, issued Mr A with two final written warnings – one for the assault and the other for his behaviour towards McIntyre – however McIntyre was unhappy with this response.
The court heard McIntyre confronted McGilp and told him he couldn't continue as supervisor while, in his view, Mr A's behaviour was not being addressed.
The ERA heard of an incident where Marino arranged a meeting with McIntyre and Mr A and McIntyre became agitated about Mr A for no apparent reason.
Marino alleged McIntyre called Mr A a "meth freak" before storming off and yelling he was "putting a PG on you c**** and youse are going down, f*** Peter."
McIntyre admitted at the hearing to calling Mr A a "f**** c***", but said he did not do this all of the time.
In its determination, member of the ERA Tania Tetitaha ruled McIntyre was unjustifiably disadvantaged by FNS's breach of the implied term of his employment contract to provide a safe workplace free from violence.
Tetitaha said there was little disagreement about Mr A's unacceptable behaviour towards not only McIntyre, but also members of the public.
However, Tetitaha said there was evidence McIntyre contributed to the situation by being overly aggressive and angry at times.
As a result, McIntyre's $10,000 payout was reduced by 50 per cent.