Keith, I would have thought that both clutches couldn't be engaged at the same time, is this not right ?
Both clutches cannot be engaged at the same time. The "shifting" valve can only address one clutch at a time or neither clutch.
No oil pressure but there is bleed down time from full pressure which is up there for those engines.
The oil pump only stops when the crankshaft stops.
The spec for the trans/torque converter/clutch pressure is 67-114 PSI at 1500 RPM.
The stall speed spec for the stock torque converter is 2500-2900 RPM. Somewhat higher on Samauto.
There will be some residual pressure to the torque converter and whichever clutch is "switched" on.
Not sure at what point, in the deceleration process, the TQ/clutch pressure and stall drops low enough to not turn a dead motor.