See, I clocked Lew's tea a long time ago...
He is used to being somewhat of the board punching bag. So when Mel trots along minding his business and the gorls decide to collectively take a swipe at her wig, Lew joins in on the mess in hopes that the focus will stay on Mel and off him. Couple that with the fact that Mel is everything Lew wants to be (light skinned, curly hair, thin, cute, etc) and you have a perfect storm.
Lew is a bully. I've noticed this trend for a while and it's disgusting.
His disdain for my sis comes from a place of self-hatred and it's time to call a thing a THING.
You can ask him right now why he has a problem with Mel and he won't be able to give a legitimate reason.