Sounds promising to me. The dark matter theory has always seemed like make-believe science.
Proposing a too-good-to-be-true engine based on an effect that so far could not be proven to exist and violates some of the most well-tested scientific theories doesn’t sound like make-believe science to you?
Now, I don’t want to completely dismiss it, but I wouldn’t call it promising. Best case, it works and we have a cool new propulsion technology and some interesting physics to explore. Worst case, it doesn’t work and this hypothesis is discarded for good. At least noone can say that these kinds of outsider ideas are supressed by the Illuminati or some other BS, so that’s a good thing.
The engine is merely one possible implication. The fact that such an engine has appeared to work is something I’d call promising. I don’t see where a well-tested theory is violated. As I understand it, the theory reconceptualizes the relationship of gravitational and inertial mass which has been heretofore asserted.
Dark matter is a convenient and perhaps not falsifiable theory created out of whole cloth.
As for suppression of science, I think that’s very real if not 100% effective.