I don't think it's a matter of "no one wants to advertise on it." With the current, and the former licensee/operator, it's a matter of going out and soliciting advertisers. To my knowledge, the station hasn't aired paid content since KSET went off-the-air.
Nets/Talk or Sports are the only remaining viable formats on AM. Music is a non-starter. With FM, HD-FM, Satellite, and Streaming, no one wants to listen to the inferior sound of music on AM. Which begs the question, why do they continue to maintain the MusicRadio 1300 format? With no paid content. Something definitely doesn't add up.
A wise man once said, "Insanity is doing the same thing over and over again, expecting different results."
It has NEVER been Houston's Tejano station, because (other than the last few months it has returned to MusicRadio 1300), it has been dark. A dark station fails to serve the public interest, convenience and necessity.