Well, you're wrong on multiple accounts.
Firstly, he's never been known for his defense. So you wouldn't be bringing him in as a defender anyways. He's just as bad as a SG defender than a SF defender, and his stats from Golden State and Charlotte prove this as he usually holds his opponent to a lower PER at the SF position than at the SG position. (IE. Higher PER differential.)
Secondly, you assume that he can't slide to the SF just because he's known as a shooting guard. Well, if you want to look at a certain shooting guard already on our team:
http://www.82games.com/0809/08POR5.HTM#bypos, you'd see that being shifted to the SF position doesn't mean you lose production. In this player's case (Roy), you'd see that he actually produces better as a SF. Richardson is the same height as Roy, but weighs more and is stronger. Why wouldn't he be able to play SF?
Thirdly, you say that small ball is bad, but we have been playing a lot of small ball for the past two years. Aldridge plays center occasionally. Outlaw is an undersized backup power-forward. Roy slides to the SF position for 25% of his minutes. Even Rudy plays at SF.
If you don't want Richardson for his general lack of defensive ability, then fine, but don't say he's unable to play the SF position when he's clearly capable of doing so.