The way the delay announcement was worded says to me that they simply didn't create much of the Themyscira content to begin with. If you have issues with the Themyscira content that needs a few more days than anticipated you could just release the rest (roughly) on time and release a patch/hotfix with the rest of the content a week or so later when it is fixed. But instead they say that if it isn't fixed in a few days it'll simply be cut and put in the next update, presumably with some of that updates content cut short because why put in the extra work if you can get away with minimal effort.
It makes no sense if the content is already fully there to not release it with a small delay/hotfix from the rest of that update's content, unless that content doesn't exist to begin with or you already plan on putting less effort into the next one and wanna pad it with content intended for this release.