Gosek was sacked in 2016 over a series of abusive, intimidatory and derogatory phone calls and text messages to seven fellow CFMEU members and his supervisor over a five-hour period.
At the time, he was suffering from depression and was unhappy that an internal investigation had not upheld allegations made by a union member he was representing. He initiated the barrage with a one-word text message saying, "Dog?"
In subsequent phone calls, Gosek called his colleagues "dogs", "dog c**ts" and "f***ing dogs", threatened to kick them out of the union or withdraw union support, hunt down and destroy them, and even challenged one to a physical fight.
In his original decision last year, Fair Work Commissioner Bernie Riordan said the use of foul language in the workplace was "unfortunate but very commonplace".
"In my experience the expression f***ing c**t, is commonly used across all walks of life in society," he said. "Inserting the word 'dog' into the phrase, does not necessarily make the phrase anymore offensive or intimidatory."
In overturning that decision earlier this year, however, the full bench of the Commission found that "in this context ... it was used to describe people that he believed had ratted on their mate" and so was "accusatory and intimidating".
Last week, Fair Work found that while the behaviour amounted to misconduct and was a valid reason for dismissal, Gosek's personal circumstances, previously unblemished work history and the impact of his sacking combined to make it "harsh".
"It is clear from the evidence that this was the first time Gosek had engaged in inappropriate conduct," the Commission said in a ruling.
"The consequences for Gosek for this one-off event are significant. He lost a secure job and his reputation amongst his fellow workers and Illawarra Coal. Gosek had to deal with a range of matters including the death of a family member, depression and physical exhaustion.
"As well, he abused alcohol with little regard to the potential impact this may have on his mental health. While none of this excuses his behaviour, we are satisfied that it is sufficient to tip the balance in favour of a finding that the dismissal was harsh."
Illawarra Coal opposed giving Gosek his job back, arguing in its submission that, among other things, doing so would be seen as condoning the conduct. Fair Work rejected this argument.
"We have made it clear that Gosek's conduct was wholly unacceptable," Fair Work said.
"On balance, we accept that the conduct was affected by a combination of circumstances or, as [his representative] put it, a perfect storm of circumstances that satisfies us that this once-off event, albeit directed at eight employees over several hours, is unlikely to be repeated.
"On balance, we have reached the conclusion that Gosek should be reinstated. We consider that it is appropriate that an order be made maintaining the continuity of employment and his period of continuous service.
"However, we do not consider it appropriate in light of the circumstances that there be any order for remuneration lost. We do so to reflect the seriousness with which we view Gosek's conduct."
A spokeswoman for South32 said, "We are aware of the Fair Work Commission's decision and are considering our position."
