You make money off your tweets? You mind if someone else does?

Interesting article about how twitter is going to be selling old archived tweets to marketers.

Old Tweets for sale


The paragraph I find interesting is: 


"This has unsurprisingly been a move condemned by privacy campaigners and it certainly does raise a few questions, however I will say this, once a tweet is published, that content is in the public domain and up for grabs, this is simply the nature of the internet."


So my question is, if you are a privacy campaigner, why would you even tweet?  Do you think this change by Twitter is another example of a companies technology that has surpassed the ability of legislation to keep up or is Twitter a giant editorial column and as such, one shouldn't have to worry about the change?