The point is, an ion engine is not some aspect of the universe that may be wrongly interpreted by contemporary physics. It is an established bit of engineering.
But that's total bullshit. Absolute nonsense.
You can't divine a mechanism's deeper nature from its name. What is a "rotary engine"? It's a rotating-piston internal combustion engine also known as the Wankel engine. And
it's a classic reciprocal-piston radial engine used in early aircraft, where the main axle is immobile and the entire engine (along with the propeller) rotates for cooling. And
it would be a valid way to describe a turbine, or an electric motor. Or any motion technology that falls outside the parameters of "linear engine".
Saying that "ion power" must refer exclusively to the probably completely useless charged-particles-as-propellant toys being tinkered with today is like saying that "rotor" must refer to the thing atop a helicopter and therefore can never credibly be part of an automobile. Not even when it's a key component of the most modern automobiles today, the ones with electric engines where "rotor" is a central component. And was a key component in the most antiquated automobiles of yesteryear, the ones with electric engines...
That said, I sort of like Dave Stern's use of the buzzword in the novel Daedalus
, where "ion cascades" are a speculative power generation or transformation technology - combined with the mention of "polaric ions" in Voyager. It's clearly something even Janeway finds impressive enough, something that could power starships or entire planets but is way too dangerous for those large scale applications and probably best confined to shuttlecraft or pocket lighters. And it's not an acronym or some other dodge - but it's not contrary to physics, either. There are many uses to an ion today, and many more will be found in the future.