First off, I do not think this problem will continue past launch in any significant fashion. At some point these “beta tourists” will come to the realization that sailing a man down by choice is an unnecessary handicap.
Currently, the beta (which should be filled with alpha testers and pre-orders) has somehow been inundated with people who bought a key off eBay. I’ve spoken to several, myself. The three-man crews seem to be either friends who want no outsiders in their ship, or non-English speakers who only want their people talking to them, in my experience so far.
As to solutions, adding a “kick” would amount to the same thing, except it would take away any chance of response.
I spent a good 40 minutes yesterday playing the first few notes of a sea shanty, then starting again from a ship’s brig, until they finally released me. Realizing the crew of mimes had no clue what they were doing, (who learns about brigs before learning how to store supplies and adjust sails?) I stuffed their remaining supplies into my pockets, gave a jaunty wave, and jumped over the side to relog and find a new crew. It was petty, I know, but made me feel better about my prison time.
Three-man locked crews would legitimize their behavior, and i’d rather see people meeting strangers, than simply locking everyone else out as a matter of course. Likewise, the time and effort to balance a three-man ship is time I’d rather see devoted to content we can all enjoy.
Here’s my two-part semi-solution: first, steer people with active in-game mics to the same instances, and those without to their own. People tend to be less a****e-ish when they have to talk to you.
Second, put a timer on the brig function so that you cannot be instantly imprisoned when you log in. A couple of minutes of interaction would make this behavior less prevalent, while still allowing the brig to serve as troll deterrent.
We locked two strangers in the brig in Sea of Thieves, but were we right to do so?
