I think you do have a good point. Of course it's not reactionless like the EM drive, but in practice, what's the difference? Both require a power source and bot

I think you do have a good point. Of course it's not reactionless like the EM drive, but in practice, what's the difference? Both require a power source and both can continue providing thrust forever without running out of reaction mass as long as they have that power source. Even the EM drive, if it works, would still need an RTG or solar panels or something to power it, and that would still limit its use for interstellar travel.