The provision about a player being entitled to a spot on the floor is not absolute.
NFHS 4-23-1 Guarding is the act of legally placing the body in the path of an offensive opponent. There is no minimum distance required between the guard and opponent, but the maximum is 6 feet when closely guarded.
Every player is entitled to a spot on the playing court provided such player gets there first without illegally contacting an opponent. A player who extends an arm, shoulder, hip or leg into the path of an opponent is not considered to have a legal position if contact occurs.
One common situation when being "there" first is does not entitle the player to that spot is when the player's chosen position is in the path of an already airborne player. I bring this up not because it has direct bearing on the OP, but because it illustrates that merely being first is not absolute.
So to ask the unpopular question: If the defensive player's foot is on the OOB line, even if he's been there since last Tuesday, did he really "get there first without illegally contacting an opponent."?