Authority member Claire English rejected his claim and said Coxhead's language towards his students was "harsh, disrespectful and did not fit with Mr Coxhead's duties of teaching, mentoring and supporting students in their learning".
Coxhead was teaching Level 3 and 4 plumbing apprentices during 2020.
In October that year he was teaching a "practical" on a block course which had been completed about 3.15pm, 45 minutes early. He told the students to go.
He then left work and ended up at a nearby pub. He found some of the older students were already there, so sat with them and had two beers before going home around 5pm.
He was invited to a disciplinary hearing by Fred Koenders, who at that time was executive dean in the Commerce and Technology faculty.
Koenders told him that block courses required a minimum number of teaching hours, so any remaining time should have been filled with other teaching activities, and that drinking with students was unprofessional behaviour.
Coxhead told Koenders that he had seen other plumbing tutors leave early, and he was not aware that drinking with students was against EIT's code of conduct.
He was given a written warning.
The following month, on November 6, EIT received a complaint from another tutor that Coxhead had not turned up to teach an evening class he had agreed to cover. Coxhead said he had forgotten and gone to an appointment concerning his health.
On November 10, an apprentice complained that Coxhead had continually verbally abused him and other students, and that "profanity was often extreme".
"Many people in the class were told they would never become qualified tradesmen, were told they were idiots and losers," the apprentice complained.
"The learning environment that Dave creates is not one that I want to be in ever again."
On the same day a plumbing company emailed EIT to say that it no longer wanted its apprentices attending the trade school if Coxhead was the tutor.
"His level of professionalism is no(n)-existent, he is derogative, aggressive and his language is absolutely shocking," the email said.
Coxhead was suspended on pay.
Called to a disciplinary meeting, he confirmed that he had called one student a "bum" and another an "effing idiot".
He told Koenders he "knew how to deal with these ratbags".
Coxhead also admitted that he had made a student cry.
English said in her decision: "Mr Coxhead explained this by saying that strong language is a feature of the plumbing workforce and that this was nothing more than the students could expect to be exposed to when they began work."
When Koenders wrote to Coxhead proposing to terminate his contract, Coxhead wrote back that he was being "singled out, and that (other named tutors) can make the same supposed breaches and no be pulled up for these".
An advocate for Coxhead told Open Justice Coxhead was "most disappointed" by the decision to dismiss his claim.