You’re right that WAS an apology.
I think the reason it took a full month for it to be issued was because the DCCC had to be horsewhipped into a corner first.
I’ll bet they were going to put out some ‘if we’ve offened anyone...........’ kind of statement. Then the Adelson lawyers got involved and wrote the apology for them, along with “either you say this, or we’ll see you in court”.
It would have simultaneously meant negative publicity for the DCCC and a massive drain on their coffers for legal expenses. I'd loved to have seen Adelson put them through the wringer.