俱舍論頌疏論本 9.70

9.70

由中可比二者，釋前妨也。由中際廣，可以比度前後二際，廣義已成，故不別說，說便無用。

Regarding "can both be inferred from the middle": this resolves the previous objection. Because the intermediate limit is extensive, one can infer the preceding and succeeding limits from it. The extensive meaning has already been established, so they are not separately taught, for doing so would be redundant.