He may have a right to 'use his foot' but the law is clear; he doesn't have a right to do a scissor kick or bicycle kick when there is risk to an opponent (without any cavaet in the law about height etc). If he'd been facing the goal, had one foot on the ground and just lifted the other foot up...
https://www.theifab.com/laws/latest/fouls-and-misconduct/#indirect-free-kick
Playing in a dangerous manner
Playing in a dangerous manner is any action that, while trying to play the ball, threatens injury to someone (including the player themself) and includes preventing a nearby opponent from...