Well, like I said, I wouldn't put myself in that situation at all. My raid doesn't take puggies along at all, and even if we did, we use a DKP system. If that puggie had more DKP than our regular Hunter by some miracle, they probably deserve the bow and aren't a PUG at all. In this make believe situation where we brought PUGs and rolled on loot, though? I would probably try talking to pickup Hunter, work out some other deal. If they wouldn't cooperate, yeah, it's pretty likely I would 'ninja' the bow over to our regular Hunter. If the PUG Hunter did a great job I'd consider letting them have it, but if they performed horribly and died pretty much right away? I'm not going to give a Legendary to dead weight, even if it's just pixels at the end of the day. They're extra pretty pixels, and they're pixels that person didn't earn.
The author of the original post also makes the argument that everyone has a breaking point, a point where they absolutely would ninja a drop. I don't think that I would personally ninja anything in any realistic scenario I'd put myself in, but there's certainly a point I would do it. I don't PUG, I make sure my smaller groups are with close friends if we don't master loot, and I really doubt that I'd be offered a million dollars to ninja some random Naxxramas item, so the life of the ninja is not for me. If I was offered a sexy mill to ninja some sword, though? Yeah, you bet I'd do it. I don't think the victim would feel so bad about it if I sent a good hundred grand his/her way to make up for it.
How about you guys? What's your breaking point? What would it take for you to ninja?
*No, that's not a word.