You're assuming China wouldn't call dibs on universal time.
The most likely scenario would be that "absolute time" would be split somewhere between China and India (so nearly half the global population would get to be close to the expected time, and everyone else would get fucked).
The only other realistic alternative is that Europe can argue hard enough to keep GMT as the primary time zone, though that sort of shit might not fly in the modern world.
Either way, the US would get fucked hard in that scenario.
Doubly so, since there've actually been studies that imply time of day can have a huge impact on things like psychological health and productivity (they usually get brought up whenever someone starts talking about getting rid of Daylight Savings Time).
Regardless, the minor things that get simplified by a single universe time would be offset by the tons of way more important things that get absolutely fucked over in the transition to it, so almost no nation on Earth would ever agree to it. Similar to how the US still refuses to adopt the Metric System or how countries with left-hand drive (probably about 30% of the world's population) refuse to switch to the right.
America is the world leader in most aspects, why would China get a say in that? Unless they just want to be stubborn, in which case they can just not be involved with the rest of the world and can go get fucked without any trade partners until they agree to use central time
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