Adding AT&T Tethering to iPhone Kills Unlimited Data

I've never had a big beef with AT&T until NOW!  I recently loaded iOS 4.3 on my iPhone 4 and wanted to turn on the new "HotSpot" feature.  I went to the AT&T "MyWireless" web site and went through the steps to modify my plan.  I thought it would be as simple as selecting tethering and paying the extra monthly charge.  Boy was I wrong!  When I got to the features selection page, this is what I found:

You can see that I am "grandfathered" into the unlimited data plan for $30/mo.  The two tethering choices include their 2GB "DataPro" plan.  Choosing either of these kills my unlimited plan according to this warning on the same page:

I wanted to make sure this was the case so I called AT&T and the agent confirmed my suspicion.  If you're grandfathered in, TURNING ON TETHERING KICKS YOU OUT OF THE UNLIMITED DATA PLAN!