Well, as others said, it isn't because you have a percentage in "sense chaos" that you will immediately know for sure someone is chaotic or is not. Stormbullies don't want to be called "kinslayer" because they fumble a sense chaos roll around the son of the khan ...
As I see it, sense chaos just give them the feeling something isn't right with this guy, a feeling that grow stronger and stronger over time, with a speed depending of their sense chaos skill (an "average" over time of the result of their sense chaos rolls). And for other peoples, the stormbully who keep saying them "you should not trust that guy", be very rude with him, probably provocating him, is just doing usual annoying stormbully stuff. Specially if the new guy is friendly and sympathetic, they'll just tell the uroxi to shut up and go look if the block is still there in Prax.
While meeting total strangers in the middle of nowhere on the other hand, storm bulls will just rely on their first impression and attack on sight every time their sense chaos alerts them.