5th foul, 30 second replacement

[donj]

NFHS

Player A1 called for 5th foul and one and one situation. Coach and player notified. Timer starts 30 second clock for replacement player to enter. During this process, coach get his players together by the bench and uses the 30 seconds as if it was a timeout. Just before horn sounds, sub reports to table and enters. Is this allowed for coach to huddle up with players for this situation? Also, team B lined up to shoot free throws while this was going on.

thanks