Hi RodgerDogger45,
I agree with you that the flextech certainly doesn’t respond like memory foam and is more likely to be either latex or some of the very high density polyfoam that is available on the market (such as the ones mentioned in post #2 here). given the price of the mattress I would vote for the polyfoam.
I would also agree that they are going for the “feel” of a more resilient “latex like” material over memory foam although both the flextech layer and the memory foam underneath it are quite thin so you would also be feeling the properties of the support layer underneath it. Even their “weightless” description seems to be somewhat of a reference to the Tempurpedic weightless mattresses which use memory foam over a similar material (in thicker layers).
Without knowing the specifics of the material I wouldn’t want to guess at how it may feel but it seems to me that it would have the surface resilience and feel of a much more resilient material than memory foam with a little bit of the softer and the slower response of memory foam (low quality/density) underneath it combined with some of the “feel” of the top few inches of the support layer.
For so called “uninformed guessing” I’d say you were right on the money 
If you buy this I’d be interested in hearing your feedback about it.
Phoenix