The logic basically goes that 3M accidentally created a force field[1] in a factory[2], factories are mostly in China now, so if "running a factory" leads to antigravity tech, China would be the ones to develop it.
As much as "I want to believe", if it's true they're not American, it's quite possible they're not alien, just foreign.
I've noticed a weird kind of racism in some folks who talk about China: they simultaneously think they'll conquer the world and that they can't invent technology on their own.
It's certainly interesting logic to conclude "If it's not American, it must be alien".
[1] https://www.wired.com/story/the-physics-of-plastic-sheets-an...