The other chiefs of the Six Gates didn't know Su Xin intended to move against the Qingcheng Sword Sect, but Huang Bingcheng did.
So, naturally, he could guess what Su Xin was up to.
Labeling the Qingcheng Sword Sect as collaborating with the Golden Khanate would be pointless, no one in the Jianghu would believe it, not even the Imperial Court itself could believe it.
So, Su Xin simply changed his approach: he didn't bring up matters of national hatred, focusing only on personal enmity.
These chiefs of the Six Gates were going to the Qingcheng Sword Sect to bring someone back for questioning. But given the current state of the Qingcheng Sword Sect, could they possibly comply and willingly return to the Six Gates for questioning?
It was even possible that the people of the Qingcheng Sword Sect would strike them down on the spot. After all, it sounded like the Six Gates were picking a quarrel for no reason, blatantly insulting the Qingcheng Sword Sect.