Yeah, there's a whole host of things you'd have to do. The variable pitch itself would probably be a show-stopper in itself, unless you made the vanes very thick at one end so that the tool would clear as it spun. If it was a static pitch, as long as you had HELICAL draft on the vanes, it'd work. I did something similar with a static pitch for a 6-lobed core (I believe it's in my photo album).
Flexibility of the part would help only slightly I think, you'd still have to worry about the tool shearing off the vane where it joins the cone, regardless of the outer edges bending.
Tough part to mold!
Question to the OP: Could the vanes be modified to make it moldable, of is that configuration absolutely needed for performance?