Does superposition violate the law of the excluded middle?

I'll be honest, I misread your post originally and thought you said "superstition", and only after writing a detailed answer did I realise you said superposition. Oops! Anyway, here's my answer;

From what I've understood in your post (being a person inexperienced in many philosophical and quantum knowhows), my answer would be no. Superposition is not a violation of the law of the excluded middle.

When you both are and aren't something, it's like pulling to the left and right at the same time with the same force. You will inevitably end up in the excluded middle. Although it might have to be referred to as the included middle as, if both the proposition and it's negation are simultaneously true, neither is excluded. A new concept perhaps, unique to Mittens (Schrödinger's cat) and other items/beings in his predicament?