Starting with 4 on the floor....

[Nevadaref]

Originally posted by blindzebra
Bench personnel entering without permission is an indirect on the coach.

Quite true, but this technical foul does not fall under the bench personnel group.
Here's why:

If this happened after a TO or intermission, then the kid is still one of the five players legally in the game and his returning is a team technical foul according to 10.1.9.
If a different kid comes onto the court, we have a substitute technical foul for either not reporting to the scorer or not being beckoned by an official.

Either way, the head coach does not receive an indirect T per the chart on page 73.

If this happened after another dead ball, then the precise call is less clear due to the change to 10-3-3. I would likely call the T under the new 10-3-3 or 10-3-7. I don't believe that I could justify a team technical here.
Therefore, this one is a player technical foul and the head coach still doesn't receive an indirect T per the chart.