The Paris St-Germain player — who is Muslim — sparked criticism when he missed a match on Saturday, apparently because he did not want to wear the design that was in support of the International Day Against Homophobia, Transphobia and Biphobia.
PSG’s manager said Gueye was absent for “personal reasons”, but it has been claimed it was actually over the strip.
Morgan has now addressed the issue in a column The Sun, saying that free speech should allow footballers to choose what they publicly support.
“Gueye is entitled to decide whether he wishes to wear rainbow colours,” he wrote.
The 57-year-old said that in Gueye’s home country of Senegal, homosexuality is illegal and can result in five years imprisonment.
Morgan said that according to a 2013 poll, 97% of the people there believe homosexuality is a way of life that society shouldn’t accept.
“Like me, you may find this horrifyingly bigoted,” he said.
“But that is the culture Gueye grew up in.”
Morgan said if the footballer was “publicly ranting homophobic bigotry” it would be a different matter.
“But he hasn’t done that, and he shouldn’t be forced to promote something he might not personally agree with nor punished for exercising his right to free speech by opting not to wear rainbow colours,” he said.
The TV star said he felt the same way about footballers taking the knee – saying that both players who chose to do it and those that don’t should all be respected.
Watch: Piers Morgan bonds with climate activist who also walked off GMB