Agree. Wikipedia gives you the solubility of K2SO4. It's soluble! The WA SOP sector is now about point of difference, real or otherwise.
Wikipedia tells us the solubility of k2SO4 at 25C is 120g/L. SO4 tell us, at an unspecified temperature, that their product has a solubility of 118g/L.
The person that put out the announcement isn't the sharpest tool in the shed.