It's not bullying. Just preconceived notions that should never have been. You don't see see them expressing it overtly. But, they sure do in their thoughts and behind your back.
I'm sure you've seen some who thought if you didn't graduate from this or that university in the PH, it means you're worthless. There are others who make fun of a dark complexion.
Anyway, back to the one complaining in the original post........
Before accusing anyone of being unfair, I would ask that guy to list down everything he did every month that deserved recognition, a pay raise, a higher pay grade, or just plain kudos and a pat on the back. If he can show that with a good history, then, he may have a good reason for complaining.