Fun read. My favorite line: "Six months later, in May 1984, Michael Larson sat beardily in the interview room for the Press Your Luck auditions in Hollywood."
To me it's just a creative way to describe his current appearance using a ("fake") adjective instead of "with a noun". Basically just turning a noun into an adjective for the fun of it. Because it's a short written piece, it's just a fun way to call attention to his having (or not having) a distinct physical appearance at two points in time.
So these aren't "real" words, and as far as I'm aware there isn't really any double entendre. It would be like saying "he sat there, t-shirt-edly, and blah blah" and then later, "he appeared, un-t-shirt-ily, blah blah" to describe him being dressed vs shirtless. Not the best example, but yea, your interpretation is correct.