Fortunately the A.R. spells out that it only resolves the conflict between safety and 4th down fumble rule, so it absolutely does not apply on other downs than 4th downs and tries (both before a team COP).
If the logic is that impetus is from B54's legal batting, and the ball is dead in possession of a player (a player of either team, as the rules are written) on/above/beyond the B's goal line, then the result should be a safety, regardless of the down.
But, that can't possibly be the intent. Try this:
1/10, A-5. Ball carrier A44 is at the A-5 when he fumbles. The ball falls to the ground at the A-4, and bounces toward A's goal line. The ball bounces/rolls into A's end zone where it is recovered by B99.
Let's see... The status of the ball was a fumble, and the fumble was by A44. The ball traveled into A's end zone from the fumble, and a player recovered the ball in A's end zone, where it became dead. Well, since impetus is from Team A's fumble, then the ruling should be a - safety - 2 points for Team A.
You'd be lynched.
The rule language needs to be edited to specify that when the ball is in possession of a defending team player on/above/behind the defending team's goal line, and the impetus is by the defending team, then that's a safety. If the ball is in possession of an attacking team player on/above/beyond the defending team's goal line, that's a touchdown. Period. OK, the 4th down/try fumble rule could cancel the score and return the ball to the spot of the fumble, but there is no way this should be ruled a safety.
Impetus is irrelevant in this case. Impetus only applies when there is a question of safety or touchback. I don't see where Shaw gets a safety out of this. (AR appeared in 2021). Such a rare circumstance, I guess most of us never vetted that AR, at the time.
This needs to be addressed. How do you get a safety out of this, when you don't on any other down? If he wants this specific circumstance to result in a safety, then change the 4th down/try fumble rule to support the AR, as an exception (to the exception).