he needs to grow a pair and breach the subject of what is obviously his desire to be your bf. This roundabout jealousy is offputting for anyone and I'm guessing it's not going to affect you in a way that will attract you to him. He obviously doesn't have any idea or is afraid to say anything. Thing is though, it seems pretty obvious but I would probably recommend you thinking this over, even if you have thought about him that way yourself.

He isn't your bf and he is showing early signs of jealousy which usually is tied to nothing but trouble in the future. If he's jealous now, it's not going to go away in a relationship either, unless it is addressed directly and he gets ahold of this behavior. In a worst case scenario you'll end up with a possessive controlling bf if you went ahead with it.

I'm not saying he's all bad but that these are early warning signs of those things and you should be careful.

Either way, you need to address this problem directly. Whether or not he remains just a friend, becomes more than that or not, the jealousy and demeaning nature he shows toward other males in your circle, is not going to be a positive influence on your relationship regardless of what it becomes.