IMO ...
The "loophole" for SQ TC is temperature restriction and reduced water usage via spray rinse instead of agitated rinse, on only the Normal/Eco cycle. The wash fill is still minimum 13 gallons (per 2019 info) for even one sock. The rinse restriction can be bypassed easily by selecting Extra Rinse. The added concession to regulations on the TRs, beyond the same temp and spray rinse on Normal/Eco as TC, is automatic water level sensing but it's not overly frugal per videos.
Consider that the Neptune TL dates back 20-ish years, early in the HE toploader curve. Calypso predates Neptune TL and is a better design. Very frugal for washing, generous for rinsing. I drained a similar whites load into my KitchenAid toploader years ago. It filled the KA to the rim of the basket, right up to the tub ring.