I understand your concern. NCAA 4-17-6 has a list of things that a defender can and cannot do once they have LGP.

When it comes to upward motion, the rule assumes that in order to draw a charge, the defender has been in the path, and continues to be in the path of the offensive player. If the defender has LGP but the offensive player changes his/her path (the Euro step for example) and then starts upward motion to shoot or pass, the defender is assumed to have lost LGP due to no longer being in the path. The onus is really on the defender to make those path adjustments and perhaps re-establish LGP before upward motion occurs.

Another example: the LGP requirements in section 4 state that the defender needs both feet on the floor and torso facing the opponent. Then, section 6 says a player that has LGP cannot lose it if they do not have two feet on the floor, or if they no longer face the opponent. In essence, you can't lose attained LGP through anything involving the feet, or turning to absorb contact. There is no such provision for the "path" requirement however. You need to be in the path to establish LGP, but there is nothing in section 6 that says you keep LGP even if you are no longer in the path, with the exception of Article 6d which does give opportunity for a defender to briefly go out of the path and move laterally to maintain. Thus, if the defender is ever out of the path (especially once the offensive player goes airborne), they lose LGP.

Put succinctly: if a defender is ever out of the path of an offensive player, they need to have gotten back into the path before upward motion occurs. If the offensive player keeps dribbling, then LGP is maintained. If the offensive player starts upward motion to shoot or pass, the defender must have gotten back in the path before the gather/upward motion. Otherwise, LGP is lost.

If that is confusing I apologize. I'll keep thinking about how I can explain it better, as I don't fully understand it myself.