Typically in music theory, we would talk about a hemiola as a rhythmic technique in which a rhythm in a simple (2) metric division is introduced in the context of a compound (3) division of the beat, or vice versa.

What the parent post describes isn't an isolated gesture like that, but a sustained state of overlapping meters, if I'm understanding correctly. In the case of the ICM described, as well as math rock/meshuggah/etc, I would describe the technique as "Polymetric" or maybe a "Sustained polyrhythm," and not a hemiola.