Aside: the more times I re-read the article the more annoyed I am with the self-righteous tone. It feels like the author is mimicking the style of legendary Usenet posts, but the story just isn’t that interesting and the writing not that witty, it falls flat.
But what about that sentence does that not make sense? They are describing tailgating..
“John regarded Mary suspiciously”
“Sharon suspected her husband of cheating. She looked through his emails suspiciously.”
"She's suspicious" can mean either that I suspect her intentions or that she suspects someone else's intentions.