At least the EmDrive is legitimately difficult to verify. It's claimed to produce tiny amounts of thrust. That requires extreme care to measure and makes it hard to see if it works as claimed.

The e-cat, on the other hand, is claimed to be a megawatt nuclear reactor. Verifying it should be easy: let it run and see if it produces power. Let it run long enough to rule out trickery like hidden batteries. If it does what the creator says it does, it should pass this test easily.

But for some reason they won't do this. They run all sorts of other weird tests but won't just demonstrate power production. To me, this makes it obvious that the "some reason" is because it doesn't work. If it worked there wouldn't be any question.