Not sure I agree. "Participation" to me is just a catch-all for badges that didn't fit into another category (since pretty much every badge could be included under "Participation" except maybe the ones currently under "Other").
So then it comes down to whether Votes are closely related to moderation enough to warrant the badges appearing in that category, rather than falling back to the catch-all.
Votes certainly have an effect in terms of moderation, -3 greys out a terrible answer, I think -4ish takes a question off the front page, as well as just generally increasing/decreasing visibility of good/bad content. Especially now that the close vote reasons have been refined and many of us find we have to just down vote questions we would previously be closing. So whilst I don't disagree that they would fit under "Participation", for me they are related enough to moderation to be a good fit for that more targeted category.
Of course it all comes down to opinion, but that in itself is a reason I wouldn't bother changing anything. Fortunately for you I have no power so my opinion matters not.