Fallacy of the excluded middle. There's other alternatives to a) saying it's outright false and b) saying it's outright true. I'm saying it shouldn't be labeled "misinformation" without extensive evidence to back it up, just as you're saying it shouldn't be labeled "truth" without the same level of evidence.
Instead, it's actually possible that we could discuss the theory as if it might be true, or false, until there's sufficient evidence to rule out one or the other. It's Pelic4n's refusal to do this that I take issue with.