Nah, it's not that, just that August 2020 is virtually empty. It's a great spot for releasing a Batman movie and would capitalize on complete lack of competition.
Also, WB set DC dates for Feb 14th, April 3rd, June 5th, and July 24th in 2020. So far two of those release dates have been used, with BoP getting moved a week. The April date is 100% not happening but I can see Batman taking the July date and getting pushed to August.