Kalle,
A more traditional punt formation would have some number of backs in the backfield area in front of the ostensible kicker, as ostensible blockers. This type of formation makes it "obvious" that a scrimmage kick will be made; thus, assuming other conditions (down/distance/field position/time) are appropriate, this is a SKF, and the numbering exceptions are permitted.
But, when those backs spread out wide, outside the tackles, they are hardly in good positions to block for the kicker. This would not be a traditional punt formation. So, the interpreter (not me) deemed that when Team A is in this wide split this formation, it is NOT obvious a scrimmage kick will be made; thus, this is not a SKF, and they are not allowed to have numbering exceptions.
I can't be specific about what prompted this AR. I can only surmise that an FBS school, somewhere, ran this type of non-SKF play (perhaps with only four linemen numbered 50-79), and it raised the issue.
Robert