If you don't want the message: don't tether.
it's a lot like stealing a car. Sure, it's not fair that certain people can afford to pay for a nice car, and you want one too so you just steal one. You can try and cover your tracks, but you're probably going to get caught eventually.
Enjoy the ride, but be prepared to lose your unlimited. AT&T WILL take it away (one of my best friends is tiered now, and he claims he only tethered 1GB or so... I don't believe that, but it doesn't matter lol...).
AT&T is a business. They make profit off of tethering. If you cheat them of that profit, they have every right to shut it down. If you don't like it, either don't do it, pay for it, or take your business elsewhere.
No biggie