If the model is out of production, I think you are in the clear, morally speaking. You did your bit, but there's only so much that you can do. The system failed you. Time to take the law into your own hands.
As a side note, I would edit your initial post to remove the mention of casting plasma guns. It gives a negative impression right off the bat. (Imagine if I had a post that went along the lines of: 'So, I beat this one guy senseless because I didn't like his accent. Would it be okay to beat someone senseless in self defense?') I don't
think your actual question is even breaking any forum rules, but I might be incorrect.
In any event, I hope that helps, and good luck with your genestealer cult. Whether you cast your cult in resin or "find one on ebay really cheap,"

I hope to see a finished product in the Showcase sometime soon!