Most of the pirates are lazy shiftless dumb as dirt Somalians anyway. The only way they get away with piracy is because their victims are unarmed girly-men afraid to fight. Chop down the Somalians rat-a-tat-tat. No great loss, plenty more where they came from.
Yeah, I hate to see people squander a business opportunity. "Welcome aboard! Here's yer machine gun. We'll have repel boarders drills just after cocktail hour..."
Darken ship sucks, I can testify from experience, and I'd be a little concerned about liability issues from some tiddly goof taking a midnight stroll and ending up swimming. Can that actually be better than issuing machine guns to drunks?
Of course not.