My problem is we have no clue what those lines actually were. If it was effectively dead code, then it's not surprising that it was untested, and the LLM-generated test wouldn't be valuable to the team. We have no clue what the value of the test actually was, and using a single stat like "lines of code covered" doesn't actually tell us anything. Saying the test was "exponentially more valuable" is pure speculation, and IMO not an especially well-founded one. (Sort of like saying people who write more lines of code are more productive.)
This speculation seems downright irresponsible when the paper specifically emphasizes that this result was a fluke. When the authors said "hit the jackpot" they did not mean "hit the jackpot with a valuable test", they meant "hit the jackpot with an outlier that somewhat artificially juked the stats." I truly believe if the LLM managed to write a unusually valuable test with such broad coverage they would have mentioned it in the qualitative discussion. Instead they went out of their way to dismiss the importance of the 1,326 figure.