I did, thanks. Their engineering blog seems important enough to them that they care how much traffic it gets from StumbleUpon. They are getting hurt and they are doing the blocking.
Imagine I said "Why Genius.com's Blog's Blocking of IE6 is Hurting Genius.com's Blog", if you like.
StumbleUpon should fix this quick and easy by changing the user agent string (overridable in the registry). The last thing the world needs is inflated IE6 stats.
The whole "companies need their internal applications" is bullshit. Firefox and Chrome do not break an installed IE6 on a computer. People can continue to use IE6 for internal sites, and a real browser for other sites.
Any IT department that forbids installation of Firefox needs to be brought outside and proverbially shot.