Jim Gannon, McGhee's successor as Motherwell manager, on Thursday claimed it was "inappropriate" for other bosses to talk about his contracted players.
But McGhee, on the eve of his first visit to Fir Park since leaving the club in June, insisted he had done nothing wrong.
"When I was asked about Jim O'Brien I was very, very careful not to transgress any rules," he said. "I have certainly done nothing that I have to be embarrassed about or answer for."
The controversy has added even more spice to Saturday's SPL clash after the first meeting between the teams this season was marred by extreme abuse directed at McGhee from a section of the Motherwell support.
But McGhee, who twice led the Lanarkshire club into Europe, was later heartened by letters and emails from Motherwell fans thanking him for his contribution.
"I'm looking forward to it," he said. "I had two great years there and have still got a lot of friends there.
"I expect there to be an element who want to abuse me but I can take it.
"I have been called everything from fat, and Scottish has been used as an insult against me. I can take all of that."
McGhee added: "The spice for me is that we're looking better.
"We have an opportunity, with Dundee United playing Celtic on Sunday, of us being able to get within two points of Dundee United.
"There is the possibility that our season is just starting now and that's the tension and that's the motivation for us.
"We feel we are probably in the best shape we have been since I got here. The players look as if we are really getting up to speed.
"I'm excited about what we're going to see from our lot, so we are full of anticipation."
Motherwell, who sit four points ahead of the Dons after losing just one of their opening 11 SPL games, are expected to have on-loan Everton goalkeeper John Ruddy back after a groin injury.
McGhee said: "I think we'll probably need two goals against Motherwell because they have been playing well.
"They have scored a few goals even though they have let some in at the other end.
"I think their goalkeeper is going to be back and he has been a huge part of their success. That will be a bonus for them."