Not just over insults, Grayson coming close to knowing Dane is a dominant omega can be dangerous for him. Dominant omega is highly sought to breed dominant children for rich alpha families. And his first impression of Grayson isnt good as well (Grayson pouring pheromone on the twin in the party)
If he was thinking about how dangerous he was he would've immediately agreed to help Joshua. Im not defending Grayson for what he has done, but he only accepted it because he was getting on his nerves. The club incident was his law straw
Yes but I think it is both, Grayson getting on his nerve and Dane sees Grayson as potential threat for trying to find the person who knocked him out, slowly discovering Dane is a dominant omega. The call from Josh happened right after the basement thing, which Dane softened his attitude thinking Grayson has some childhood trauma but the club scene just erased all his pitiness towards Grayson again.
Also some small details is cut but in the novel after Grayson says Dane must be a special omega, Dane immediately thinks he definitely cannot leave Grayson alone. He was very triggered everytime Grayson come close to his omega identity
Dane is doing all of this over some insults. Having him go off a cliff is crazy