How was the 8472 supposed to respond? He wasn't even on his ship. Voyager hails it, gives them two seconds to reply, then tries tractoring it, beaming it away and boards it. Yeah if I came upon a group of strange looking people digging in my house, I'd give a hostile reaction too. Especially later on when they're helping my greatest enemy. Dangerous? Sure I'll give you that. Enemy? Only because Janeway picked sides because she needed something from the Borg. So yes, they were innocent before Janeway started annihilating them at the cellular level because she needed something. Which ironically enough the deal with the devil wasn't honored, surprise.
So you're saying Janeway wouldn't use that dead slug(if you have a better term let me know) to save her crew from a Krenim attack? She would think it's better to die that defile that dead person? I don't agree at all. We've seen several times she's guilt ridden over her choice to strand them there, and she'll twist herself in circles to justify questionable choices. As damaged as Equinox was, Ransom probably came to the same choice, with Max encouraging it all the way. They were under attack, under threat, and needed to get away. After that, I bet Ransom resisted using another one until they were under attack again, then did it again. Maybe by this time Max was synthesizing more behind his back... well it's done, is he not to use it. He can't fire Max since he's already short handed, so they're going home and Ransom seemed ready to take responsibility for the choices of his crew at that time. I don't think Janeway's immune to that sort of slippery slope at all. She killed Tuvix after all simply because she liked Neelix and Tuvok more. It's the same sort of situation where you're weighing two bads against each other. Though Janeway didn't have an evil redhsirt whispering poison into his ears. Just Neelix.