he didn't charge across the locker room. IK told Geno he didn't dare say it to his face. Geno came across the locker room and said it to his face...IK punched him.
That's what actually happened.
"Enemkpali challenged Smith to say it to his face. Smith did and pointed his finger in Enemkpali’s face, which then led to Enemkpali punching Smith and breaking his jaw."
http://nypost.com/2015/08/13/geno-smith-said-to-need-wake-up-call-after-instigating-jaw-punch/
I guess Geno could have been a pussy and walked out of the locker room when IK said "say it to my face." Im sure that would have won just as much respect in the locker room as getting punched in the face.
In the end, he probably should have just paid the $600...but a guy making $600k a year shouldn't be punching people in the face over $600,
especially when the guy missed the flight due to a death in the family.
Id say IK is just as much of an asshole for wanting $600 when he knows the guy didnt make it because a family member died.