The few times i've tested KH jail glitch. I havent had any problems with others being about. I've seen others glitching, but leave them to thier business, as I hope they do for me. As for KH only working for some people, i'll bet they are the ones brave enough to ride it through (your health goes to 0)
I dont glitch alot, but it gives me something to do with my abandoned lvl32 pirate, testing the ones I know and if they've been fixed or not.
Zeppers Lvl40
http://pirates.teamofx.us