The veteran republican dismissed jibes from Assembly opposition benches, including one reference to him as “your highness” and a comparison with North Korean dictator Kim Jong Un, as he faced questions on the furore around the creation of the new £75,000 a year post.
Deputy First Minister Mr McGuinness and First Minister Arlene Foster have faced criticism for exercising the Royal Prerogative to enable them to appoint BBC editor David Gordon to the job without having to advertise the press secretary position through open competition.
The prerogative powers essentially enabled the ministers to amend employment law without the need for approval by the wider Assembly.
The use of the mechanism has angered political rivals, who have accused the Sinn Fein/|DUP administration of engaging in a secretive abuse of power.
Mr McGuinness, who fielded a barrage of questions on the issue in the Assembly chamber on Monday, branded the controversy a nonsensical “two day wonder” perpetuated by “anoraks”.
Ulster Unionist Jo Anne Dobson had asked him how a “proud republican” felt in exercising the powers of a monarch.
“I feel grand, absolutely grand,” replied the Sinn Fein minister.
“Anything that benefits the working of the Executive and, by extension, enriches the lives of the people we represent, is a good thing.
“I have done many things over the course of the last 20 years, none of which I am ashamed of whatsoever because I think my contribution to this process has put us all where we are today.”
Mrs Dobson’s party colleague Steve Aiken then asked: “What further advice can we expect from Kim Jong Un on message management within the Northern Ireland Executive?”
Mr McGuinness branded his remarks “silly and childish”.
Earlier, Alliance deputy leader Naomi Long had suggested MLAs refer to the Deputy First Minister as “your highness”.
Meanwhile, Traditional Unionist Voice (TUV) leader Jim Allister questioned whether he planned to invoke the prerogative powers again.
“Is the Deputy First Minister intending to further abuse the Royal Prerogative by usurping the legislative functions of this House?” he asked.
Mr McGuinness defended the appointment process.
“There was absolutely no secrecy or underhand dealings, some minority members can laugh all they like but the appointment of the press secretary was legally compliant,” he said.
He said he was “not in the least concerned” about a debate he claimed was confined to social media.
“It’s all about anoraks, it’s all about the opposition,” he said.
Mr McGuinness added: “This is all nonsense folks - this is all a two day wonder.
“The reality you have to deal with is that David Gordon will soon be in post and we have every confidence in his ability to do the job and I think the fact that he is going to do the job is what’s scaring the opposition parties more than most.”