@MitchW People find explanations or reasons to justify their prevailing opinion. So rather than accept he did something inappropriate, they find weird justifications to satisfy their views. It was an “awkward autistic moment”, or “he got carried away”. It’s actually an Occam’s Razor situation: the most straightforward explanation is the truth; he did a Nazi Salute. But admitting that means admitting you support/enjoy the activities of a Nazi.