The relationship between Brooklyn Nets guard Kyrie Irving and Nike is likely severed for good, the shoe giant's co-founder told CNBC.

"I would doubt that we go back," co-founder Phil Knight said in an interview that aired Thursday. "But I don't know for sure."

Nike announced last Friday that it has "suspended" its relationship with Irving and canceled its plans to release his next signature shoe, part of the massive fallout that followed his tweeting a link to a film containing antisemitic material.

The Nets also suspended Irving for at least five games; he has missed four already.

Irving signed with Nike in 2011 and has had a signature line of shoes since 2014, with his annual endorsement deal believed to be worth at least $11 million.

"Kyrie stepped over the line," Knight said. "It's kind of that simple. He made some statements that we just can't abide by and that's why we ended the relationship. And I was fine with that."

Irving posted a since-deleted tweet last month with a link to a documentary that includes Holocaust denial and conspiracy theories about Jewish people. In a contentious postgame interview session a couple days later, Irving defended his right to post what he wants.

The Nets said they decided to suspend Irving in part because he "refused to unequivocally say he has no antisemitic beliefs." Nike evidently also tried to get Irving to clarify or apologize.

"Same situation. He was dug in," Knight said.

Irving eventually made an Instagram post after the Nets announced their decision to suspend him, writing in part, "To All Jewish families and Communities that are hurt and affected from my post, I am deeply sorry to have caused you pain, and I apologize."

A day later, Nike suspended its Irving relationship.

Irving has also been criticized by several anti-hate groups, including the Anti-Defamation League, as well as NBA Commissioner Adam Silver. Irving and Silver met earlier this week in New York to discuss the situation, one of many conditions the Nets wanted Irving to complete before they will reinstate him.

A small group of protesters were outside of Barclays Center before the team played the New York Knicks on Wednesday night, saying Irving has been treated unfairly by the team and others for speaking his mind.

"We look at who we sign and how much we pay and we look not only at how good the athlete is but what his or her character are," Knight said. "It's not an exact science, but it's a process that we go through with a lot of intensity and with a lot of people sticking their hand in it."

Irving has expressed no shortage of controversial opinions during his career. He repeatedly questioned whether the Earth was round before eventually apologizing to science teachers. After the pandemic hit in 2020, he urged players to consider not participating in the season resumption inside a bubble at Walt Disney World in Florida. And last year, his refusal to get a COVID-19 vaccine led to him being banned from playing in most of the Nets' home games.