When you finalize a logo, you typically run a quick due diligence (a Google search) to see if you reinvented a wheel. If you did, you scrape it and start afresh. Tox didn't do that and they should've.
If they came up with it independently(a very legitimate question given the similarity of the --- very nice by the way --- logo, but one they seem to have evidence for) then there seems to be no moral problem or even a legal issue.
You're basically claiming "I thought of it first, there for it's mine" which is both legally wrong in the US for copyright(independent creation is a defense) and morally bullshit in the same way that Amazon's one click ordering patent is.
Seems like you're invested up to the point when you're wrong, which is a pattern I've observed on this site in general.
Incidentally, your anecdotal "feelings" about whether something feels original or not make for a pretty weak argument.