I think you two are stating the rule correctly, just worded different.
Ball and player have to be fully in forecourt to make an over-and-back call possible. I saw a ref stop a high-school game and quickly demonstrate the rule to a complaining coach, who had it wrong. (Ref did it quickly, with a smile... Coach got it, wasn't mad, and apologized for the yelling... One of the best ref/coach exchanges I've ever seen in THOUSANDS of in-person games over the years.)
The key here is, was Aidan's right heel still touching the halfcourt line before he stepped back? VERY close call. If his heel wasn't touching the line before he moved it back, then it was over and back, the bad guys' ball. If it was still touching (again, very close, would take a super-hi-def replay to see that), then he was fine to step back and no call should have been made.
Of course, in the NBA, this would have been an eight-minute break while the refs went to the table and studied the replay from 405 slightly-differing angles.