Did it occur that both of you guys aren't too far apart from each other? You both concede that bones survive over 65 million years, you both concede that some of our materials will survive over 65 million years. You both concede it'll be the vast minority of those things.
The only difference is of opinion is would we connect the dots if we did find something created by the Voth. Being how different they are and all they may well have a different set of tools with those three fingered hands of theirs and all. I'm inclined to think at the very least any artifacts we found from the Voth would raise red flags, even if we couldn't figure them out today. Though it might give the alien intervention folks something new to rail on.