The problem for Disneyland is they don’t want another “measles outbreak” situation on their hands and to have to deal with the very aggressive state government. They also want to appeal to the comfort and safety of most guests.
So with that in mind as I see it the options are:
1) Follow the CDC and the science and loosen mask restrictions and risk a “mini outbreak” linked back to the park. This is higher risk solution.
2) in addition to loosening masking - Require testing and/or vaccine passports similar to what venues like the Hollywood bowl are doing. Medium risk. Even if someone falsifies information to enter the park, WDC has plausible deniability that safety protocols/screenings were exercised.
3) keep the mask mandate in place for now, but maybe begin to loosen it for pictures, expand “dining areas”, similar to WDW. But ensure queues and most spaces require it. This is the safest option, as it demonstrates a slow easing of the restrictions without wading into the (unfortunate) politics of mandatory vaccines.