I've called things shaped like this "polyentendre".

In my head I think of it has just really high linguistic compression. Minus intent, it is just superimposing multiple true statements into a small set of glyphs/phonemes.

Its always really context sensitive. Context is the shared dictionary of linguistic compression, and you need to hijack it to get more meanings out of words.

Places to get more compression in:

- Ambiguity of subject/object with vague pronouns (and membership in plural pronouns)

- Ambiguity of English word-meaning collisions

- Lack of specificity in word choice.

- Ambiguity of emphasis in written language or delivery. They can come out a bit flat verbally.

A group people in a situation:

- A is ill

- B poisoned A

- C is horrified about the situation but too afraid to say anything

- D thinks A is faking it.

- E is just really cool

"They really are sick" is uttered by an observer and we don't know how much of the above they have insight into.

I just get a kick out of finding statements like this for fun in my life. Doing it with intent is more complicated.

What the author describes seems more like strategic ambiguity but slightly more specific. I don't think it is a useful label they try to cast here.