If your talking to Guard units, they are so damn picky (pointy nose units) they tell everyone to go heavies. I know alot men that they told the same thing too.
Good luck, go for it and shop around. Here is something else to think about. Right now, everyone in the Guard is getting over manned with pilots, even heavies. They may be saying this to you because your chances of getting picked up and actually becoming a military pilot may be better at a heavy unit. Just a thought.