Time out after IW

[DC_Ref12]

Ball is on the floor and players are scrambling for it. No one has control. Coach B calls for a timeout, my partner blows his whistle and immediately realizes he screwed up. Tells the coach he can't grant him the time out because it was an inadvertent whistle and that we're going to the arrow to determine posession. Coach says, "Ok, the ball is dead, now can I call a timeout?"

My partner denies his request and says only after the ball becomes live and your team has posession and/or the ball becomes dead again after it has become live.

I was looking in my rule book and couldn't find an applicable case play. Can a coach call timeout on an inadvertent whistle?

Thanks.