I think our TG's move at 32 knots. So they will out run the resupply.
To add on to what you were saying Tyrannis, if no one does anything for maybe 30 minutes after announcement, the TG will automatically steer itself towards the Supply Convoy or start making a sector wide circle, waiting for the Supply Convoy? Just having the announcement alone, people are not likely to notice it, even if the TG is in bad shape. You would be able to override the TG's auto wait for supply, but it will give you a pop up window telling you this. Something like, "Warning! Supply Convoy in route. If you wish to proceed, a delay in resupply/repair may occur. Do you still wish to proceed with your command?".
Either way, a +1 on this.