Even though Mirror-verse already gave us a Ratchet in mostly white (originally using the Energon Roadblock crane-truck mould in a comic, but then using the Combiner Wars Ratchet mould for a Convention custom toy), I thought that Ratchet would look better coloured like a 1985 Constructicon (which I think were actually coloured like Ratchet in the FunPub Mirrorverse comics)... because I was remembering how FunPub would try to colour characters based on an opposing characters if possible. And a green/purple colouring reminded me of that green "movie" coloured Ehobby Ratchet from about a decade ago.
(I had initially thought FunPub had done a SG Ratchet toy, done in white and blue... but it was actually SG Soundwave, which used the Ratchet mould.)