Joe Gorman, 27, was signed by Portadown last week, with the Shamrock Park club announcing the news on Saturday via social media.
Posting a photo of the Dubliner, Portadown FC said: “Portadown Football Club is delighted to announce the signing of 27-year-old Irish defender Joe Gorman, who was most recently with Galway United.”
However, many comments on Facebook and Twitter referred to a tweet in 2014 when Mr Gorman was a youth team footballer at the Scottish club Inverness Caledonian Thistle.
He tweeted: “Ross Kemp in Belfast talking about the Troubles. Wouldn’t you just love to open up on all them Orangemen.”
He was suspended by Inverness after that tweet appeared.
Actor and documentary maker Ross Kemp was in Belfast at an Orange parade which had been blocked by police on the Woodvale Road.
Mr Gorman also played at Airdrie as well as Bray Wanderers and Drogheda United in the League of Ireland.
Portadown’s announcement of his signing sparked a backlash with one person saying: “Portadown have now sunk to a new low, I for one will not be going to support any team this individual is playing in.”
Another said: “Joe Gorman if you’re a real man well stand up and apologise to the Orange men, plus to the people of Portadown who will be paying you wages which I’m sure isn’t cheap.”
Supporting Mr Gorman, another person stated: “I’m sure there is not one man/woman on here who have commented that have never been in a position of regret and have needed someone to hold out a hand and offer them a second chance.
“If you can introduce me to someone who has never made a mistake then I’ll happily shake their hand.
“Disgraceful tweet yes but how long ago was it? Maybe the lad has made better choices since the tweet and tried to better himself as a human being or maybe he hasn’t and needs to stand up and apologise, but even if he did would it be good enough for people? Surely we all deserve a 2nd shot at being a better person.
“Northern Ireland is a bitter bitter place and his tweet didn’t help his cause but we choose to move on or move back.”