"Guard players from abuse" - swarms of players afk en masse on ships as it is, abusing the system. I'm not saying a kick option is free from abuse, but the abuse it dishes out will certainly be less damaging and destructive than it is now. Will captains kick everyone right before they port? yes, on a rare occasion, but it's better than getting swarmed with afkers without stopping them every time.
Why don't we get off the boot option for a moment, and discuss a different option. Blacklisting/ignoring players so they cant come back to future runs. They wont get kicked when black listed, but they will be unable to board again.