I think it's a bit absurd that someone would argue that being potion-like and something you drink is "not a liquid".
That's far greater reaching that assuming something you drink falls into "other liquids".
I can understand the design behind making potion glutton not work with extracts, to keep them from being overpowered, however, to assume this ruling extends to other effects, is ridiculous.
If that ruling was intended to work with other effects (which existed at the time that potion glutton was changed to reflect the distinction of excluding extracts), then they would have been changed as well.
The writers may not have known about an ability or feat or trait when creating a new one, but when errata happens, they review other relevant cases.
Potion Glutton was changed because comparatively to other ways to drink potions and liquids, it was far FAR more powerful than something like Accelerated Drinker, A sipping jacked, or this Blade and Tanker feat.
Extracts are absolutely liquids, anyone arguing they're not is insane or being willfully dishonest with simple definitions.