TIme outs

[Nevadaref]

I believe that this situation would fall under 5.8.3 Situation E.
"The official erroneously grants Team B a time-out in a situation when Team B cannot have one. What happens now? RULING: Team B is entitled to use the time-out since it was granted. The time-out once granted cannot be revoked and is charged to Team B. All privileges and rights permitted during a charged time-out are available to both teams."

The official shouldn't have granted that assistant coach's request, but since he did and the guy did ask for it, you have to charge it and the technical foul for an excess time-out too.