“Obviously he did that and nothing happened,” said Tiafoe.
“I think that’s comical, but it is what it is.
“Nothing happened, so there’s nothing really to talk about. Obviously it’s not consistent, so it is what it is.”
The incident had similarities to when Novak Djokovic was disqualified from the US Open in 2020 for mistakenly striking a line judge in the throat when he hit a ball towards the back of the court.
“Honestly it was really unlucky coincidence,” said Musetti.
“I was a little bit, honestly, scared, because I really didn’t want to harm nobody, of course.
“I immediately went to the line umpire, and I of course said sorry. I apologise to everyone.
“It was right to have a warning, but I think the umpire saw that there was no intention about that, and that’s why he probably just let me continue my game.”
Musetti will face defending champion Carlos Alcaraz in the final four.