The effects of thrust are also relative. If, for example, the otherwise micro-thrust of this EM drive was put on a craft equipped with a mass-negator (anti-gravity), the resulting acceleration and speed could be staggering. And yes, mass-negation has been demonstrated through experiments with fast-rotating magnetic fields.
Throw a trillion dollars in black money at all this for the last few decades (or more) and who knows what the government is sitting on!
The TR3B or one of its variants aka “Mysterious Black Triangles”