Remember I mentioned Vanessa Tan who had an IE-only policy at work? Now, the policy is official and an unbendable rule (my understanding was that Vanessa was able to use it somehow, before). Read her farewell to Firefox.
Much has been sacrificed in the name of security.
Of course, that bit is debatable (because IE is intrinsically insecure, though Firefox is not without its problems, as its security has been called into question recently). I shan't go there. But please, don't bring up the point of security via obscurity (because I believe there is no way you can prove it is true until Firefox is as widely-used as IE).
Back to the blog title: how would you feel if your organization refused you the freedom of using your preferred browser (assuming that it isn't IE that you dig)? Would you take it lying down, or would you take reactive action? Remember this is different from an IT policy that, for example, forbids you from installing unlicensed software or software that is particularly vulnerable to security risks (I'm tempted to say IE here). Firefox is neither unlicensed software, nor is it as vulnerable to security risks as the software you are (hypothetically) being forced to use (IE). I know I wouldn't be happy. You might as well take away my Internet connection (which just may happen at work, soon, but for other reasons).