But the original quedstion was about etiquette and the pirate flag, and proper etiquette for a pirate is "Whatever I damned well want it to be!"
Absolutely and that's it in a nut shell, it is your personal POV
My POV is some what different in that I think some, and I might even go as far as say few, take it all that seriously.
We have Sailing Clubs & Sailing Associations and Maritime Museums all putting on festivals all the time with Pirates themes; The Festival of Sails just ended here in SD, had some 20 Tall ships from all over the place here for 5 days, the theme of the Festival was ??? Pirates, a few of them will go to DP, then over to cat Island, the theme ??? priates
I quarantee ya, they and the 10's of thousands that participated in the festival are not out to glorify rape, plumder & murder, they are out to have fun and enjoy the sailing with their friends and family
So to the question of flying a pirate flag , fly it where ever you choose, to the question of etiquette, don't fly it above the Stars & Stripes when on the same staff or halyard
That's from another point of veiw of course