I'm sorry, but what the hell is this mentality of "don't use social networks, you'll get a virus". The probability of you getting a tweet / message with a link to an infected page is already pretty low. Now if you did receive one - would you be dumb enough to click the link? Supposing you did - I don't believe this thing saying going on the page will get you infected; maybe for IE6, but pretty much all new browsers are sandboxed and have security features. If tomorrow Google gave you a link to infected content; would you stop using Google for that?
And come on, there's more of a chance of you getting a virus while watching pron or whatnot.
Also, "hacked" accounts get removed in minutes. If you were Twitter, wouldn't you find it weird when one of your users started spamming with obfuscated links?