Ah, but:
It's up to the Premier League to determine hat is blocked. It is not up to the ISPs to check.
It does seem that the ISPs should check with the Premier League first, but from the article referenced, this has been going in for a while, and as this affects sites that are not implicated in this issue, I think it's reasonable to unilaterally lift blocks. If the Premier League can't provide accurate information pertaining to the target site, then I don't see why the order should be followed. Just shows them to be bungling idiots.