Yep, even if the clock has stopped, when the ball is snapped, the clock starts again, so it's running, you can spike the ball. Total BS call on the refs, just one of quite a few questionable decisions they made in that game.
Lattimore didn't hold, he never restricted London's route and Pitts definitely caught that ball took 2 steps up field got popped and fumbled before the half and that wasn't even looked at by review booth.