I would argue that the failure in the presence of an alternate means to facilitate decryption is a negater of the whole "effectively" clause. That's okay though. Civil disobedience is the best way to go I'm afraid.
At first glance, the "effectively" does seem rather silly, especially when applied to weak DRM that's more or less trivially cracked. But the "ordinary course of its operation" is what gives it force, by protecting DRM from being disqualified as ineffective when subjected to conditions beyond ordinary operation. It's not a question of whether the DRM is robust against attack, but whether it normally presents any real barrier to non-hackers.
"Effectively" in legal terms means "to have an effect" (as in any effect at all), not that it has to be "effective" as in "good at it's job."
The plain English meaning of the word isn't really useful here.
All "effectively" in laws such as this (and the European equivalents) means that there has to actually be some mechanism of protection, i.e. you can't just have a file full of junk binary in the directory called "DRM" that doesn't do anything and claim circumvention by deleting it. But there is clearly an effect here.