Well, I brought this up with Mr. Culexus and this is what he said:
"I don't like to jump to conclusions, but I do kinda think so.
One main reason, I guess would be the fact that, generally, Cultists were never drawn with wheels on their backs. They were always drawn with trophy racks (just a basic 3 prongs). I ignorantly drew cultist with a chaos wheel/star instead. A female cultist with redeyes and a chaos wheel? Could just be a coincidence.
Very likely. But I will wonder."
I never even thought that the wheel could be exclusive to Cultist-chan, though now that he mentioned it, I've also always only seen the three-prongs-version. In addition to the wheel and the eyes, though, it's also the same hair colour and fairly similar clothing (just no bare belly). Plus the "Dranonish" CSM. And since the day we've seen LIIVI in Ascension I thought Black Crusade should feature a guest appearance of Cultist-chan (even wrote so on the forums), so this is kinda what I was sort of hoping for.
Maybe I'm thinking too much into it, but for me it looks close enough to Cultist and Dranon to qualify as an inside joke. Similar to LIIVI, or the "Drive me closer"-Commissar in the DoW2 expansion.