I will concede that you're partly right. It was because the Lord wasn't answering Saul that Saul sought Samuel out (2 Sam 28). This isn't intercession. However, I would point out that Samuel chastises Saul for asking what will happen of him rather than the Lord. The point is that if your not right with the Lord, at least well enough to pray to Him, then there is no point in seeking anyone else out.
If you want to say I'm trashing the Catholics then fine.
That's a very different claim from "it's always wrong to talk to 'dead' people" or "talking to 'dead' people is necessarily necromancy". I don't object to your reformulation, at least not much.
If you think it's necessary to trash Catholics, I think that's too bad. But if you make up claims about what Scripture says that are at variance with the little leather Bible I keep in my desk drawer, don't be surprised if I call you on it.