In the the rule it states "for the purpose of punishing the opponent", so yes, backchecking being the purpose of multiple strides eliminates it from being charaging because hte purpose was to prevent the goal, not to punish the opponent.
Directly from the 2020-21 rule book on NHL.com:
Rule 42 - Charging
42.1 Charging - A minor or major penalty shall be imposed on a player
who skates, jumps into or charges an opponent in any manner.
Charging shall mean the actions of a player who, as a result of distance traveled, shall violently check an opponent in any manner. A “charge” may be the result of a check into the boards, into the goal frame or in open ice.
A minor, major or a major and a game misconduct shall be imposed on a player who charges a goalkeeper while the goalkeeper is within his goal crease.
A goalkeeper is not “fair game” just because he is outside the goal crease area. The appropriate penalty should be assessed in every case where an opposing player makes unnecessary contact with a goalkeeper. However, incidental contact, at the discretion of the Referee, will be permitted when the goalkeeper is in the act of playing the puck outside his goal crease provided the attacking player has made a reasonable effort to avoid such contact.
42.2 Minor Penalty - The Referee, at his discretion, may assess a minor penalty, based on the degree of violence of the check, to a player guilty of charging an opponent.
42.3 Major Penalty – The Referee, at his discretion, may assess a major penalty, based on the degree of violence of the check, to a player guilty of charging an opponent (see 42.5).
42.4 Match Penalty – The Referee, at his discretion, may assess a match penalty if, in his judgment, the player attempted to or deliberately injured his opponent by charging.
42.5 Game Misconduct Penalty - When a major penalty is imposed under this rule for a foul resulting in an injury to the face or head of an opponent, a game misconduct shall be imposed.
42.6 Fines and Suspensions – Refer to Rule 23.6 – Fines and Suspensions – Physical Fouls Category.
If deemed appropriate, supplementary discipline can be applied by the Commissioner at his discretion (refer to Rule 28).
Regardless, if skating half the ice and hitting a defenceless opponent when the best way to prevent a goal was to clearly seal the post isn’t for the purpose of punishing an opponent, I don’t know what is. That’s predatory as hell.
I’m sure as hell not an expert on the rule book, so if there’s another section I’m missing that relates to charging you can provide, I’ll gladly read it.