Blocking browsing from IE6

Found on the expanses of the World an interesting script that blocks the viewing of the site from IE6. Perhaps this will seem to someone a great dirty trick for users, but apparently this is one of the ways to force the user to upgrade to IE7 or switch to a normal browser. The script uses jQuery .
Actually, IE 6 Blocker Script

UPD.
I do not in any way raise the question to get away from the cross-browser layout.
If you look at the work of the script, you will see that the layer on which the “pseudo-alert” hangs has transparency (although you can change it) and everything that is on the page is quite legible. So it will not save from visible jambs. This is just an evil message to the user to upgrade.
UPD2
bolk suggested a more humane way