Tina Fey staying away from Twitterdom

According to her interview with Craig Ferguson, Tina Fey stated that she refuses to go on Twitter for two reasons. The first being that she would become too involved in it but the more important reason being that it would give away too much of her humor. I thought the second reason to be particularly interesting. Do comedians lose some of their interest outside of Twitter because they are giving away too much? Maybe that's why I incessantly watch 30 Rock or Baby Mama over and over again. I can get my Tina Fey fix which if she was on Twitter I wouldn't need to watch her actual live stuff. I would just follow her life there.

Is this a smart move or do you think that she should just give in?