[Rob1968]

Wow! This thread is the result of yet another case of poor wording by the editors of the Rules Book.
It seems to me that in 4-23 - Guarding, and 4-37 - Rebounding, and 4-45 - Verticality, there are two subjects addressed, in very sloppily structured paragraphs, or Articles.
4-23-1, third sentence, deals with players on the playing court, without reference to LGP: "Every player is entitled to a spot on the playing court provided such player gets there first without illegally contacting an opponent."
The following sentence introduces that statement's relation to actions of opponents: "A player who extends an arm, shoulder, hip or leg into the path of an opponent is not considered to have legal guarding position if contact occurs." Such action can occur whether or not the player is guarding an opponent.
4-23-2 defines an intial LGP, which is a new subject. It is not intended to define a "player position".

4-37-1 defines rebounding.
4-37-2 describes obtaining or maintaining legal rebounding position.
4-37-2 d. states: "To obtain or maintain legal rebounding position, a player may not: Violate the principle of verticality."
And 4-37-3 reiterates the statement in 4-23-1, regarding player position. Thus, in rebounding, guarding is not neccessarily involved, but verticality is.

4-45 begins with "Verticality applies to a legal (player) position." It is
not a statement about LGP.
Then, Articles 1-7 deal with Verticality, in reference to opponents, and thus, LGP.
Although it is an extrapolation, the common understanding of Verticality is that it applies to a player having the right to his place when in contact with the floor, and when jumping within his vertical area. The notion that when a player,/defender jumps "within his vertical area" he forfeits his right to verticality, seems anathema to the generally accepted legal/illegal actions of players, whether they are, at that moment, in offensive or defensive attitude.
Thus, Cameron, I respectfully disagree with your stance on the subject.