The Author Is Hardly Skeptical
He is making a stretch hypothesis not supported by the rover team with the same type of streach your senses type of approach in the Mars face crowd. Anytime someone asks you to squint as part of your analysis alarm bells should ring. First look for a chemical explanation then look for a biological one if chemistry doesn't suffice. This article barely touches the chemical explanations already released by the rover team.
Regards,
Mark