He doesn't think you are, you actually are. It's just a common courtesy. But you are not obligated to follow it.
Hum. I'd say I'm able to register my interest too. I don't believe I'm stepping on his toes just by doing so. As I said, if it comes down to me and him, I'll let him have it.
And I already intended my willingness to buy one a long time ago, in my WTB thread.
I just made a separate thread in order to get more visibility.