Rules support?

[fullor30]

I've looked(sort of) and can't find. This was told to me by a dad of a player of B team who is a new ref.
Coach A calls a thirty, official reports. Team A sits down, Team B also sits. Scorer(Cheseagle, where are you?) decides to change from 30 to full as teams are sitting. Coach A now pizzed because he called a thirty and starts on table and official(best defense is a good offense)

Do you warn team to get off their butts and if they don't give a DOG warning or more severe?

Obviously bad game management not to catch. Boys varsity 3 man.