i would keep him if you know you can take care of him. he seems like a calm lizard if all of his care requirements are being met. if a monitor is too cold or sick he will seem like he's "tame" but he just cant fight back like a healthy monitor would. your monitor sounds good though. quick question, whats his basking temp?

as for you doing anything wrong i didnt notice anything but you did say you were messing with his hide? leave his hide alone. thats his sanctuary. if he cant feel secure in his hide he wont feel secure in his cage.