The other option is test cruises, social distancing and masks on board, and they've made no motions towards a test cruise model. Several have been approved from Florida; for an AK season they'd have to get the Wonder to Seattle and test cruise there, and have the crew vaccinated. For a mid-July sailing they're already running short on time for "staff, Seattle, vax," even without test sailings - and the full vax crew is necessary for a 95% sailing without test cruises.
Most lines are getting their crews in, vaccinating, and then doing quarantine and testing. For a lot of crew, it's not possible to get them vaccinated in their home countries. (And they cannot even bring in crew from India right now.) A two-shot cycle requires 6-7 weeks; a one-shot cycle is still going to be 28 days per data and recommendation for full effectiveness. And it's already May 29. The calendar math is super-shaky even if the plan is get crew to Florida, vax 'em, and use the voyage time through the PC as the quarantine period.