I don't see why this is different than any other example of a live band playing a copyrighted song on a TV show - someone fills out a cue sheet, someone sends the appropriate royalty payment to BMI or ASCAP, and it doesn't get an article in Variety because it's perfectly routine.
The lawsuits filed by Lee Mendelson Productions, as mentioned in the article, appear to involve recordings of Vince Guaraldi performances of the song being used for promotional/commercial purposes, which is something different than what happened on Colbert's show.