Hello, and enjoy your stay.
Seriously though guys, why just immediately accuse him of being an Alt?
This may not be his first online community Forum, and a fair ammount of other forums have Welcoming boards where you make a topic to introduce yourself. We may not have one, but it may seem normal to others to introduce themselves.
Just because we've had problems with a couple of idiots coming back with Alt accounts doesn't mean than absolutely everyone who does something that they tend to do, is them.
And the whole "Denying = Lying" thing is just stupid. Of course an innocent person will deny something. Why would they openly admit that they did something (Or are someone, in this case) if they didn't/aren't?
Heck, even he does turn out to be an Alt, and I'm not saying he is, it doesn't mean you have to jump on absolutely everyone else who introduces themselves.