As a mere reader, if non-US-flagged ships aren't allowed to stop at two consecutive US ports, then it seems likely they'd head to California instead of Hawaii,

As a mere reader, if non-US-flagged ships aren't allowed to stop at two consecutive US ports, then it seems likely they'd head to California instead of Hawaii, since it is the larger market, leaving Hawaii, which would otherwise receive cheap cargo on a mid-way stop, instead having to them import it from the mainland, so paying shipping for both the initial foreign-to-mainland trip and then a low-competition and more expensive US-flagged mainland-to-Hawaii trip. If they could stop at Hawaii before and then after mainland, then they could drop off containers when passing each way, lowering Hawaii's costs.