You do have to do that, at all times. It's called "being a functioning member of society" – and that means being considerate of other people's views and feelings, as ridiculous as they may be. Everybody does this, all of the time (well, maybe some people don't. Those people are usually dicks.)

Remember The Guardian isn't a satirical magazine, but a newspaper. It doesn't have the defence against purposeful offence that comes with the former.

If you are a newspaper you have to write news. If you care about peoples feelings, they should create a tumblr blog instead.

And how facts could be offensive or hurtful?

Makes you think about their motives for adding such an exceptional warning.

Ball gripping fear?

Very likely. I heard an two-way interview on NPR with the editor of the Washington Post, another editor from a prominent UK paper (either the Observer or Guardian, can't remember and can't find the episode, but both are members of the same media group) and the anchor.

The editor of the Observer(?) and WaPo were duking it out because the editor of the Observer admitted that he and his staff were frankly terrified of reprisals, and that it was important to admit that publicly, especially if a paper makes the decision not to republish, and that appealing to "sensitivity" as a reason for not republishing the cartoons was a cop-out. The WaPo editor stood by the "sensitivity" excuses. I obviously completely agree with the former.