Very Simple
First this all happened in less then 2 minutes. these aren't models and they do not react real fast.
It takes time to flood down and opening the vents whille there is crew on deck is not done in peacetime. This is Very risky to anyone on deck.
It is very clear to anyone who knows the Ohio class that the tug was struck by the port side verticle stabilizer fin and holed, the tug sank very quickly, as they just do that when you put a hole in one.
Navy2000 has served on several USN Subs and he know how quickly ...or not so quickly reports and then orders are given to counteract what was transpiring topside and a 560 foot sub does not responde that quickly at this slow speed on the surface. By the time the Georgia swung her rudder hard over and the tug regained power, it was just too late.