I can tell you that we don't have a policy for inflight as far as upgrading goes. As far as Flight Attendants are concerned, upgrading is done at the gate. If you want to move someone up to a (rarely) vacant First Class seat, we are supposed to wait until we've reached cruise altitude as it can only be done once the door is closed and once the door is closed on the ground - passengers must remain seated until the sign goes out. I know, I know, this isn't always the way it goes, but that's what's written as far as a policy of any kind goes.

I can't answer for the FA the OP was referring to. For myself, and any other FA I've flown with, I can't imagine discriminating on the basis of race. We are Alaska Airlines. We fly many native folks within , to and to and from the state of Alaska. We have many MVP Gold members that are Native American. They sit in First Class routinely. These people pay my salary. The only plausible explanation I can imagine is that the OP was not appropriately dressed? I have no idea what that would mean because people wear denim routinely in FC. Was it ripped denim? Were the clothes visibly dirty? Was the t-shirt clean and without holes? I can't imagine anyone denying an upgrade simply because one was wearing a pair of nice jeans and a nice t-shirt. We don't really have a "dress code" for First Class and, for me, I wouldn't deny someone if they were Gold because of any of these things unless it was really extreme. I would never have handled it the way the FA in question did though. I would have probably just smiled and said, "thank you so much for being with us today - we appreciate your business and please let me know if I can do anything for you." and then moved on.