But if the value of the anomaly is that it can jump without refueling, then it seems - given comm lag times - you're never going to be able to catch up to it.

Of course, the AN couldn't actually jump that fast, since it required 1-6 weeks to recharge after each jump. And it is reasonable to assume that - absent an emergency - the derelict ship's computer would be set to recharge prior to jumping.

So that answers the question of why everybody isn't rushing to waylay this ship.

From the POV of those watching events from each inner system concerned, all they see is a ship that doesn't identify itself dropping into the outer system, refueling from an uncharted chunk of ice and then departing again. Only in a system where even the smallest chunks of ice were charted would this sequence of events not hold up.

Of course, the IN *would* be interesting in catching the ship. But they'd be interested in doing so because it was behaving like a pirate/spy, not because it was an example of supervaluable tech.