But Mr Edwards has denied threatening Mr Selwyn or ever sending any abusive text messages.
The authority was shown text messages which Mr Selwyn said he had forwarded to himself from a work phone - but Mr Edwards told APNZ there was "no proof" he had sent the original messages.
Asked if he had called Mr Selwyn a f***wit, he said: "No, I didn't say that".
Mr Edwards said he did not dismiss Mr Selwyn, having called him the next day to ask him to why he was not at work.
A previous authority ruling shows Mr Selwyn was awarded $3000 in compensation for hurt and humiliation after he was made redundant from another drain-laying position in 2007.
Mr Edwards said he would challenge the authority's ruling.
In her finding, authority member Rachel Larmer rejected Mr Edwards' claim that Mr Selwyn was hired as a worker but later agreed to become an independent contractor.
She found Mr Selwyn was unjustifiably dismissed and was entitled to payment for lost income, unpaid wages and outstanding holiday pay.
But she reduced Mr Selwyn's compensation entitlement from $4000 to $3400 because he had contributed to the situation leading to his dismissal by directing the hard-fill to the wrong address.
Mr Selwyn could not be reached for comment.