Legal Guarding Position on sideline

[CoachW]

This is my first time posting after reading for a few months. I think I have learned a lot about the rules and what officials expect from coaches (and hopefully I don't come across the same way as BBallCoach).

I was reading rule 4-23, and know that you cannot have a foot OOB to get legal guarding position. In 4-23-3 it says that the guard is not required to have both feet on the playing court after LGP is obtained. Does this mean that once you have it, the defender can slide over and get one foot OOB and not have it be an automatic block call, and if not can somebody please explain why, because it seems to me that they can have a foot OOB and still take a charge once they originally have LGP.

Thank you in advance for your replies.