I can completely understand ruger not wanting to touch it. *can* they work on it? Of course. But ruger isn't your local gunsmith. They're manufacturers. If they make it and its wrong, they'll fix it. If they make it, billybob buys it, does who knows what to it besides screw it up, they're not going to try to figure it out, and then be stuck warranting the work if billybob did something else they didn't find and its still screwed up.
If I buy a f150 and rip the engine out and drop in something else and it runs badly, ford definitely doesn't want it back although a local mechanic will probably help you figure it out.
I'm guessing there was a reason it was on the used shelves, and it's in the first post.