I don't know if Luke is sour about that fight and what went on but in my opinion he has every right to be fucked off about how everything went down.
Firstly he wasn't even surposed to fight Yoel. Yoel was a short notice replacement to the end of Lukes training camp, So all the training Luke did was for a completely different style.
And to ad salt to the wound Yoel missed fucking weight which is the biggest dick move there is.
I get that Luke isn't always the most likable guy in the media or anything but I personally love his fighting style and I have to say If I was in his shoes i would be pretty fucked off about how that all went down.