I don't see how tweeting recruits is "creepy" unless you include something personal. "Come to Our State!" or "#hailstate" is creepy? How is it any different than a billboard except that it's electronic? You really think it's creepier than weird crayon drawings with stick figures and "you're a baller" written on them? Not even close.
The AD putting up a billboard and the coaches sending a letter is not the same thing as Joe Blow 40 year old from Aberdeen sending a message to a 17 year old high school kid that he does not know. Said fan then follows the happenings of this croot through Twitter and/or Facebook and talks about the kid's weekend activities with his buddies. He may even follow the recruit's mom's twitter account. Then the croot ends up at a different school and the old weirdo gets his feelings hurt and cusses the kid with his buddies.
Now you can say my scenario is way over the top and doesn't happen often. I then point you to this board, ED, the Spirit, Gene's, or any other SEC program's board during recruiting season. It is creepy. And Twitter is the gateway drug of recruiting these days.