Belichick was asked Monday to explain Butler's benching for fans wondering why the cornerback didn't play in New England's 41-33 loss to the Philadelphia Eagles.
"I appreciate the question, but it would be a much longer discussion," Belichick said. "There are a lot of things that go into that. In the end, the final decision is what I said it was."
After the game Sunday night, Belichick had said it wasn't a disciplinary decision.
"We put the players and game plan out there that we thought would be the best, like we always do," he said Sunday.
That Butler wasn't a part of the game plan was a surprise, as he played 97.8 percent of the defensive snaps in the regular season.
Butler said after the game that the Patriots "gave up" on him and that he "could have changed that game."
"I respect Malcolm's competitiveness, and I'm sure that he felt like he could have helped," Belichick said Monday. "I'm sure other players felt the same way. In the end, we have to make the decisions that we feel are best for the football team, and that's what we did, that's what I did."
Former Patriots linebacker Rob Ninkovich, speaking Monday on WEEI, questioned the decision to bench Butler.
"I mean, if it was discipline, I don't know if that is the best way to go about it," said Ninkovich, who was on two Super Bowl-winning teams with the Patriots. "You need good players on the field to execute. Bill says it all the time, Bill will say it in interviews, 'Coaches don't win games, players do. Coaches lose games.' At the end of the day you have to have your best players on the field, and you question if Malcolm not being on the field is the best option to win the football game. At the end of the day, it is what it is. That is what happened. It is in history now.
"For Malcolm, what is best for him is hit free agency. He is going to go to another team here and probably get paid accordingly. I wish nothing but the best for him and hope he continues to play at a high level that we have all seen."
Butler played just one snap in Super Bowl LII, on the punt return team. Eric Rowe started in his place at cornerback.