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The knowledge that we have gained from this experiment is that the experimental data disagrees with the theoretical justificiation for the idea. That isn't the same as proving that the theory is wrong, even if that seems the more likely explanation. To be sure that the theory is wrong we would need an analysis of why that is the case and what were the false assumptions and faulty reasoning behind it. Any volounteers?

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The original theoretical justification for why the EmDrive was supposed to work was also wrong. The idea was to use a cavity shaped like a truncated cone, such that the forces on the big end and the small end don't precisely cancel. But this neglects the force on the sloping sides, which (of course) balances everything out.

Here's a detailed analysis by Greg Egan showing why the EmDrive would not be theoretically expected to generate any thrust: https://www.gregegan.net/SCIENCE/Cavity/Cavity.html

Proponents tried to hand-wave these arguments away and claim that the EmDrive's empirical results were explained by new, unknown physics.

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