2X difference doesn't matter to a reasonably constructed cryptographic threat model. Any threat model for which a 2X difference is meaningful is already flawed. I'm not saying a 2X difference doesn't matter in general. I'm saying a reasonably constructed cryptographic threat model is going to consider attacks as either "worth worrying about" or "not worth worrying about", and any maybes, like the possibility of an attacker who already controls $20M finding another $20M, fall in the "worth worrying about" bucket.
It could make the difference of mounting a hash collision before a certificate expires or after (2X time), if the attack doesn't yield to parallelism and time becomes a limiting factor.
The claim was about a 1 bit reduction in entropy. A scenario like that definitely acts differently, but it's not searching a space either; reducing a guaranteed calculation time by 2x is not really comparable to a loss of 1 entropy bit.
