Your brother is as stupid as my mom, she thinks unpluging the keyboard will give her a virus.
And whats with the avatar? Didnt know we could have em, not that I want one.
You can't have them. I just tried. I uploaded the image at the bottom of the page.
EDIT: Some more people have them :( The forums just hate me.
Anyway, calling someone's brother stupid wouldn't seem like a good argument.
Perhaps your brother could get on IM with someone, post here, or join the #RTB irc chat. I assure you that RTB won't damage your computer, or blockland, and you can still run the original version of BL even with RTB installed. This goes for anymod. RTB contains no exe's, which gives you a chance to look over the code, as well as no compiled scripts. With both of these advantages, it would be fairly difficult to put any kind of malicous code in. It is also downloaded as a .zip file, which can prevent it from being executed immediatley, if there was anything to execute.
Finally, if RTB happens to damage your computer, you have the name of the webhost, authors, and all that other information, so forming a case would be fairly easy.