This title is completely misleading and paints the government here in a false light. It is clear to me from the original article that the GCHQ staff were ensuring that hard drives ALREADY slated for destruction by the Guardian were complying with their required destruction process for classified information. They were not destroying hard drives owned by a private corporation without their consent or seizing hard drives. I know it is tempting to read only one side of a story and jump on reactionary headlines, but let's try to continue giving benefit of the doubt to both parties like rational humans.
Hmm, I don't think that's entirely true - supposedly they were told "You've had your debate. There's no need to write any more." and "You've had your fun. Now we want the stuff back." Those quotes suggest they didn't intent on destroying their computers with a copy of the data they were working on.
I don't think it is. It seems pretty clear you misunderstood. As posted in another comment, this Tweet shows that The Guardian destroyed the hard drives at the government's behest: https://twitter.com/dansabbagh/status/369794535464767488
This is all very unclear to me. There's quite a bit indignation here which may be clouding people's rational assessment of the situation.
The Guardian has clear motive to play up any interaction like this with the government. That doesn't mean they would, but I'm not going to suspend critical assessment of the situation just because it plays to be beliefs.
The ratio of verified information to editorializing rants is very low here, at the moment.