"It's time. Use everything you have on hand now guys. We either win it here or lose."
Logically, there should be no reason to rush things since if they proceeded with the steady pace they were going at, the Kobold King would eventually be defeated. The problem, however, lied in the word 'when'. If they took too long that a guild team showed up, Sato and the others would end up in trouble. The best-case scenario was the guild offering their 'help' while the worst-case scenario would be a 'mantis stalking the cicada unaware of the oriole behind' scene. They would just end up doing everything for a group of strangers to swoop in for the kill. Hence Sato gave the order to everything they had on hand.