Speaking of the hammerhead badge...You can also recieve that if you help repel the massive random attack of scrapyarders on the Arachnos outpost. I've only seen it once, although I haven't spent that much time on Sharkhead. Was lovely fun though, seeing them splatter against the drones and my team
As for taking Scrapyard down...It is hard, yes, and you'll need more than one team unless you outlevel them by a buttload. The burning patches from the demolishers in his entourage hurts like -heck-, even if they're all grey to ye.
Narisha, Lvl 34 MM Nin/Dark