Oh I agree with you completely....and with his super pushy (atleast initially) attitude my guess was that he was gelded late! He is also the leader of the herd already, and his somewhat studdy manners may be what has landed him all of the lovely bite scars on his neck and body!
I am with you there, no worries! I mean really, he's a gelding...the only thing registration, or knowing lineage would do for me is give me a potential heads up to problems and an exact birthdate.
If he's all arab, I'm cool with that! He's a little guy, but I'm only 5'3" so that works just fine for me!