Star Wars and Star Trek are the two biggest sci-fi properties in history, so it makes sense to take on one with the other.
As mentioned, Star Wars Galaxy’s Edge will be at Walt Disney World before you know it and Universal is sure to want to combat that with something.
Also, while Star Trek has a massive history to draw from that would allow for many potential attractions, it’s also received new life in recent years thanks to new movies and an even newer TV series, so it’s a current name that is exciting again.
As with all unnamed sources, we need to take this idea with a grain of salt, but there are many reasons why the rumor is so attractive.