The rule makes sense. Not having at least 5 players with linemen numbers..

can confuse the defense as to who is eligible to receive a pass.
Linemen can report in as receivers, but receivers can't report in as linemen
The rule is relaxed for a punt I think.
However, when the ND player lined up behind the center that made the set-up not a punt formation.
That specific rules expert is generally clumsy with his wording, but he got the call right

Post updated for clarity