[esquivalience]

Respectfully, you inferred the conclusion "So clearly it must be some variety of that!". GF doesn't say that, they merely say it may be like that and that the explanation given in the article doesn't agree with their experience.

[mekoka]

Respectfully, GF quite explicitly also dismissed the claim that it is agave.

Meanwhile the article states that there is established scientific evidence that it is (probably the Sesalana species), in the form of an 89% DNA match, but more likely the trunk part of the plant rather than the root (as initially claimed by vendors).