* they did pretty much all of the things you would like to see (such as reversing the direction and making sure the thrust reverses).
* they seem to have done a thoughtful and careful job, including testing in vacuum.
So, I still think they are likely wrong, but this ups the ante. In my opinion, you can't just say "this is obviously wrong."
Sure I can. Was the apparatus temperature controlled during the vacuum test? Was it tested in all orientations (not just backwards) to remove any gyroscopic weirdness from the rotation of the earth (think Michelson-Morley experiment). Was there EM coupling between the cavity, the torsion balance, and the chamber that could manifest as an anomalous torque, not thrust (that is, did they just make a big brushless motor)? Does the instrument register a thrust when the cavity is radiating but is bolted to the chamber floor and not the balance? Is there no thrust when it's oriented orthogonally? Does it still work if the power supply is electrically isolated from the vacuum chamber without a common return (ie did they build an electron gun)?