Eh, it's hard to tell if 8472 would have carried out their threat to destroy other races after they destroyed the Borg. Their state of mind at the time was, there was no difference between the Borg and the rest of the galaxy. Given what we know in In The Flesh, they are reasonable people, and it might have turned into a Minbari situation. But I guess, given the information Janeway had at the time, it was reasonable to assume they were savages.
I would still say it puts her in the 'Other' category, because her motives at the time were strictly selfish, and she later disowned her actions when she found out they caused other worlds to get assimilated.