best guess is that the Varner vs. Cerrone (WEC championship fight) is still fresh in Chael's memory. In it Varner won early rounds and was ahead but Cerrone had all the momentum and looked like he was on his way to KO Varner but threw a knee as Varner was going down and the ref paused the fight for "knee downed opponent" and Varner pleaded that they stop the fight, claimed he couldn't continue because of the knee (which frankly was .01 of a second away from being legal)... so they stopped it and it went to judges cards and Varner won; only except when they gave Varner the mic in the post-fight he said it was his hand and some other stuff that was hurt, nothing to do with the knee, seemed very clear at that time he wanted the fight stopped because he was about to lose.
It actually led to tons of bad blood and Cerrone beating Varner down in a rematch after Varner lost the title to Bendo.
that being said Varner 2.0, is not the same Varner that was in the WEC, many people have alluded to how hes changed and is a different guy now, and also the broken leg was evident and can be seen on many replays.