Why did Ofcom back down over DRM at the BBC?

Cory Doctorow is in fine form over at the Guardian today.

"So when Ofcom told Auntie that it hadn't made the case for DRM, that the social harms outweighed the benefits, and that it wouldn't allow the BBC to add DRM after all, it seemed like the regulator had really stepped up to do its duty: protecting the public interest, protecting the rights of disabled people, protecting the rights of British firms to field innovative new devices into the British marketplace.
And then Ofcom caved. In its latest consultation on the matter, Ofcom takes it as a given that the BBC will be allowed to add DRM to our licence-funded television signals. Instead of asking whether there is a case for DRM, Ofcom offers up a string of "have you stopped beating your wife yet?" questions, like, "Do you agree that the BBC's proposed approach for implementing content management would safeguard citizens' and consumers' legitimate use of HD content, and if not, what additional guarantees would be appropriate?"
Did you catch that? Not "Can DRM be used to safeguard legitimate uses?" but rather, "Which DRM should we use to make sure this happens?"

[...] the BBC has been told by its licensors that they won't allow their programmes to be aired in high-def without DRM... But how credulous do you have to be to take a threat like this seriously?

[...] The FCC caved, just like Ofcom...

So we sued... 

The court agreed with us. They recognised that being a telcoms regulator doesn't give you the right to regulate receivers and the devices they connect to. The Broadcast Flag died before it could be enacted."

Brilliant as ever.