Assertions without evidence are just that, assertions. Despite his high academic ranking all this professor is providing, in this instance, are various logical fallacies, not least of which is the personal incredulity fallacy. And all the watchtower are doing is their usual argument from authority fallacy.
I notice neither party says anything that can be remotely tested (i.e. have the evidence flung in their faces) and instead relies on science-like phrases that will impress those without the understanding to know better...