It's highly likely the satellite can measure the ping delay to the nearest microsecond. That would translate to about two city blocks. Not GPS quality, but more than good enough to aid this investigation. Remember, it's through a vacuum (mostly). And there are no routers in between.
You have no idea of how far off the synchronization is.
It could be off by minutes. The crew pulled the breaker on the processor, and all that was running was a periodic handshake.