[M&M Guy]

I don't think the tableside official (C) was caught off-guard; it looks like he points to the T that he's ready after the conversation with the coach. However, it is possible the C was using the "old" throw-in mechanic; back when the T handed the ball for the throw-in, the C would cheat back to cover any quick turnovers because the T would likely be caught up in traffic and not make it back to cover the play.

This very play illustrates why the mechanic was changed; when the T bounces the ball and backs up, it frees them to be able to cover the quick turnovers, allowing the C to be in position to officiate in the front court.