"Appeal to authority" is a fallacious rhetorical tactic only in an extraordinarily rigorous epistemological context, in which all truths need to be established from first principles. In practice, especially given the information asymmetry between the people that have devoted rigorous study to a thing and the people that think they know about it because making computers do things means they're smart (which is an intellectual pathology that I think ought to bother anyone who cares about the process of modeling physical phenomena accurately and honestly, even if it doesn't bother you), an argument like "physicists uniformly agree on this physical property" is a perfectly adequate assertion in favor of the claims made in the article. It would for sure be bolstered by the inclusion of sources, but you have to admit that you're throwing away a lot of relevant information towards the end of supporting your intuitive sense about how the optics here work. It's not impossible, in the absence of an argument from first principles to counter, that you're correct and that people who have formally studied physics and/or are familiar with the literature are wrong or misguided, but it sure isn't the most likely case by a wide margin. In that context, your certainty ("I don't think the details of his argument can be [correct]") seems much less well-founded.