Why would a guy don't want to meet his gf parents if he been with her for two years?

He may be resisting because this is a part of a natural progression from friendship to dating to engagement to marriage. She wants to know if you are acceptable to the family. Your move.

Well there could be a number of reasons like scared, nervous or he simply doesn't think you guys will last or that serious but I truly don't know for sure since obviously I'm not him but it's odd for him not to want to meet them cause he can't avoid them for ever 

Because he's not having a relationship with his girlfriend's parents.  Duh...