Delays in end game

[so cal lurker]

HS. White is winning, black scrambling to catch up. With about thirty seconds left (and no time outs) black scores and a black player grabs the ball and holds it.

What’s the best way to handle? In the game I was watching, the ref blew the whistle (I think gave a DOG, but not sure—I was in the stands) and let Black sub and put in their defenders to press. Is that the best path, or would it be better for the ref to just let the clock keep running and tell the player to drop the ball? Blowing the whistle gave black 6-7 extra seconds, the ability to set their press, and the ability to sub.

(Same thing happened a second time, when black scored to come within 3 with 7 seconds left—this time the ref did nothing, and the game ended, followed by a black player flinging his mouth piece while glaring at the ref.)