I agree with you about Twitter. I don’t require it, and In stay off. Too many sharks. Maybe Sarah thinks that no matter where she posts, the haters will find her and spew their venom just for that pathetic, futile pleasure.
Also, once you have been as world famous as Sarah has been, it’s hard to stay under a safe though distant rock on the beach. A part of you remains an extrovert, who still wants that hot blinding light of attention. Mitt probably feels that way too. Look where he is now, and with all his surplus Millions. They are both hooked as with Show Business.
Sarah Palin is a public figure, so no doubt finds it convenient to put out a single announcement on twitter. That’s better than fielding numerous queries.