So, there is an actual utility for it, it's just not people centric.
Having a framework for how you convert the clock measurements from the lunar reference frame to terrestrial reference frame is helpful for orbital maneuvering and navigation, as well as communication coordination.

They're not building a "UTC+5” style timezone, but a "given the moons mass and orbit, here's how we define the time ratio between the earth and moon so we can consistently calibrate our clocks".