I could be wrong but IIRC this was one of the things that set off Mark David Chapman to murder Lennon.
Mark Chapman got John Lennon’s autograph and stuck around afterwards to kill him. Clearly Lennon’s remark didn’t offend him enough to stop him from asking for a sacred autograph a decade and a half after the remark.
It was. He also felt Lennon was a bad influence on kids with the drugs and stuff and he thought he would be like Holden Caulfield from Catcher in the rye and save the kids before they went off the cliff, and in his mind that meant killing Lennon. Now he gives a whole different excuse, that he wanted to steal his fame which is baloney, he probably says that to appease the parole board. When he was arrested he constantly talked about the Catcher in the rye book.