TL;DR
Rejection of a patent is considered success for Ask Patents community, so shouldn't the icon for rejected tag be a greenish-thumbs-up instead of current reddish-thumbs-down ()?
Rejection of a patent is considered a success (...patents which have been successfully narrowed or rejected...) and Ask Patents community is congratulated on successful rejection of a patent (...Thanks to the YOU, the Ask Patents community...).
As per Wikipedia article on "Thumbs Signal", thumbs-up often has a positive connotation (except in Germany, France, and Hungary), while thumbs-down often has a negative connotation. Similarly, in symbols, green is often used to represent "success", while red is usually reserved for "failure".
So while the current icon () may make sense from USPTO's perspective or from applicant's perspective, but from Ask Patents' user's perspective, I believe that the icon for rejected tag should be a greenish-thumbs-up instead of current reddish-thumbs-down.