This option would be abused severely. Suppose you go on a public ship, your captain is a troll, and you go out for an hour run, all the while you are repairing, cannoning, and being a great team player. Then when your Captain has 16 skull loot chest, 4 rare ship chest, he decides to start kicking players off his ship.
Wouldnt be fair would it? all that work for what? so he could take what ye can, give nothing back. What options would we have, no one would be crew everyone would want to be captain. So even though I wish I could boot them off my ship, I truly wouldnt want that option available.
I dont know what or how we can stop people from going afk, some are now letting their ships sink and only taking those that participate back out with them.