Rodney Quigley, an independent member representing Ballymena, was commenting after a judge denied Michelle O'Neill any damages in her legal action against Mr Carson.
Councillor Carson wrote on Facebook in April 2021 that the new DUP leader would put Michelle O'Neill "back in her kennel".
He was suspended from serving as a councillor for three months in 2022 by the Northern Ireland Local Commissioner for Standards over the comments.
Then in January 2023, the Belfast Telegraph reported councillor Carson as saying he had been "sacked" from the DUP.
In a final hearing on Tuesday in the High Court, Master Bell said that Ms O'Neill was entitled to no money as a result of the online remark, saying that "in my view, no president or prime minister, nor any member of the public, will think of her reputation in reduced terms as a result of it".
Both Mr Carson and Ms O’Neill must pay their own costs of about £13,000 each.
The judge also indicated that it was a minor case which should never have reached the High Court, saying: "When the court’s time is taken up with cases involving disputes between politicians involving insults which one imagines are sometimes heard in school playgrounds or outside pubs on Saturday nights, then serious cases… inevitably suffer delay."
Councillor Quigley, who is also an influential figure in the local bands scene, told the News Letter "it was wrong what John Carson did," but that bad things are said online all the time with "never a word about it" in the courts.
Councillor Quigley said: "I feel the judge made the right decision, and came to the conclusion it should never have reached that level.
"I'm not defending the remarks. I think they were wrong. But I feel it should never have reached the level that it did.
"It's a waste of public money... I know John Carson has to pay his own legal bills. But certainly there's a cost to the taxpayer or the ratepayer.
"You have to pay a judge. You have to pay people to listen to the case, you have to pay admin. And in my opinion, that's a waste of money."
Mr Carson had been a DUP member since at least 1993 when he first stood unsuccessfully for what was then Ballymena Borough Council.
He was elected first in 2005, then in 2011, 2014, and 2019 (by which time it had become Mid And East Antrim Borough Council).
Rodney Quigley was elected alongside him as an independent in 2019.