It's very simple: if you don't have the right to be offended, then you don't have freedom of thought, much less freedom of speech.
That you cite Rowan Atkinson's support of free speech as a defense is incredibly ironic. He's not saying you don't have a right to be offended or to express it, it's that you don't have a right to expect the government to act on that offense, and I'm in full agreement.
I think you're treating "I feel offended" as equivalent to "I wish to suppress someone else's speech" or even "someone is required to care that I feel offended", when they don't necessarily follow each other.
Everyone has an inalienable right to get offended. What they don't have a right to is for anyone to give a shit about it.
I hope now you can understand why my mind was boggled.
EDIT: Also, please note that I very intentionally did not call you stupid, I called your comment stupid.