I recall reading somewhere that DCU was practically finished and ready to launch when it was announced the AT&T purchase was going to finally close. Thus, WB/DC already had this service ready to go and they wanted to get it out there. AT&T brass thought it was odd they wouldn't wait, but it was too late to push the brakes from their side.
I have been saying and stand by the notion that DCU NEEDS to be a subset/division of HBO Max. It should be super simple and will expose all of the HBO Max subscribers to the DC brand. To me, it should be a no-brainer decision.
Launch HBO Max on your tv or other device > go to the icon for DC Universe
That's literally how it should be and I sincerely hope they end up going that route. That way comics are still available for those who want that, the animated shows, movies, etc. will still be there and then they can decide to keep originals on there that HBO Max subscribers can have access to.
Just do it AT&T.