This might be completely daft, but hear me out at least. Feel free to cut this theory to shreds if you notice anything that doesn't fit.
Unless it's the spelling of Kathryn. I think that's it, but I'm not certain. I know of so many different Kathryns and Cathrines and Katherines and so on that they all blend together. :rolleyes:
I think Bosun Krebbs is a stealth cameo from Kate Capsize.
She gives her name in Club 41 as "Kathryn C Krebbs", and as far as I remember, she is only referred to as "Kathryn" or "Bosun Krebbs" in the trial, but the credits list her as "Kathryn 'Kate' Krebbs". Was she ever called "Kate" in the game? I don't recall...
It's humorously revealed at Club 41 that our Guybrush Ulysses Threepwood isn't her Guybrush Q Threepwood, but this may not be entirely true. Perhaps it's like this: our Guybrush meets Capsize, charters her boat, etc, and they go their separate ways.
Later, unknown to us, the other Guybrush meets Capsize, and does all those terrible things to her. At some point, he destroys her reputation, and she decides to start a new life as Krebbs. Much later, she ends up on Flotsam, and hears about the trial, so she decides to join in and get her revenge.
She could easily dye and cut her hair, so that wouldn't be a problem.
And if she continued to have trouble with Guybrush Q Threepwood after changing her identity, that would explain why she doesn't remind our Guybrush that she was originally Capsize - she thinks he already knows. And after the reveal, it doesn't matter, because she would think they've never met before Flotsam.
There it is, go for it!
Telltale Staff: if I'm right, do I get a prize? :)