In the NFL's NFC Divisional playoff game on 2018-01-14 between Minnesota and New Orleans, Minnesota's Stephon Diggs scored a touchdown as time expired in the fourth quarter to take the lead and thus win the game. Of course, the game does not end till the PAT is attempted.
Diggs removed and threw his helmet in jubilation. The back judge threw a flag, presumably for unsportsmanlike conduct, but this penalty was never announced. Why not?
The players, media, coaches, staff, and security rushed the field. After about ten minutes, the officials were able to get everyone off the field and the Minnesota offense on the field for a PAT attempt. Why was delay-of-game not called against the Vikings?
The Saints were not there, and it took another minute or so to get eight Saints onto the field and onsides before the Vikings could snap and kneel-down. Why was delay-of-game not called against the Saints?
The real reason is, of course, everyone had been caught up in the moment; it was an exceptional ending to the game. Further, any penalty would have been toothless and silly.
Is there any guideline the NFL uses to withhold a penalty call due to unusual celebrations or mass reactions like this? Or, did the officials simply use their discretion to avoid a silly but correct call when it doesn't matter?