From the FFG Rules Reference document:
RANGE
"Range is the distance between two ships as measured by the range ruler"
Autothrusters refers to Range, thats it.
Obstacle placement in the setup also refers to Range. So, tell me where are the 2 ships you measure distance between when you place your asteroids?
Whilst I understand the reasoning behind the question you are asking (being that it specifically refers to the words ships) you could just as easily replace the word "ships" in the opening sentence of the range section with a broad generically inclusive term (such as "in game element" for example covering ships, asteroids, debris, bombs, mines etc.) which would solve your question but it would not change the original debate, simply because "Range for an Attack" is specifically separated as its own definition.
You can't use the definition for the stuff you agree with and change it for the stuff you do not agree with. You either use it for everything as written or you conclude the definition is wrong.