As someone who enjoys open crewing, I've had a staggering amount of griefers joining my crew lately, and doing what griefers do (toss blunderbuss at me, light the ship on fire, anchor the ship or drive it into an Island, toss loot and supplies overboard, etc).
Galleons and Brigs both have ways of dealing with griefers, by having a majority vote to lock up said griefers. As things currently stand, sloop players have no such way to deal with griefers like that and it actively discourages using open crew on sloops. With the Captaincy update, I see no reason why Sloop Captains shouldn't be able to kick griefers (or at the very least prohibit them from interacting with anything on the ship).
I already know the usual responses to this kind of suggestion so I'll address those:
"What's to stop sloop captains from kicking someone just so a friend can join?"
Well while that's a fair point, I have to ask how exactly is that any worse than a griefer joining a captained Sloop and sabotaging the captain's ship and loot? You could argue that the Sloop captain is taking a risk of being joined by a griefer by using open crew, but then I could counter that by saying someone who joins a captained Sloop would be choosing to risk being kicked.
Another usual response to this topic is "Don't use open crew and just use discord or the forums", but like... if the only answer to sloop griefing is to not use open crew than doesn't that point out a massive flaw in the system? Galleons and Brigs both have ways of dealing with griefers, but Sloops do not and with the captaincy update it seems kinda silly that Sloop captains can lose control of their ship because of a griefer.
I can understand not letting Galleon or Brig crews kick people, because that would absolutely be abused, but Sloop CAPTAINS should really be given a way of dealing with griefers since as of right now they have none and are actively discouraged from using open crew.
TL;DR: Sloop Captains should be given a way of dealing with open crew griefers that doesn't just boil down to not using open crew. Not having a way to deal with griefers has been a unique problem for Sloops for far too long, and now that players can straight up be the captain of their sloop, they should be given a way to deal with griefers.
Again, the fact that the only given solution against Sloop griefers is for people to NOT use an in-game system, shows a glaring flaw in that system.