Timeout changes your teams offense and defence to better suit for opponent's style of play, so its never unnecessary. ;)
BB doesn't have NBA or FIBA rules,but more like a mixture of both and some own BB-rules (atleast about technical fouls and timeouts).
Coaches job is to make anything he can to help team win. Timeouts are his way of doing this. I think his current attitude on timeouts is biggest flaw in his actions to do so. I'd fire him if I could. XD