can you go to prison for enticing an undercover FBI agent?

An Alabama judge threw out an Internet sting case because there was no actual child victim. A 50-year-old man made an Internet connection with someone he thought was a 15-year-old girl. Instead, he was conversing with an FBI agent. The judge's order:

Specifically, there was no actual "victim"; a thirty-seven (37) year old male undercover FBI agent was the actual person who interacted with the Defendant during the course of the investigation and at all times was the individual with whom the Defendant interacted making the basis of the allegations here.

This makes sense to me. How can we convict someone of enticing a minor if there is no minor involved? The defendant imagines that he is interacting with a child but there is no child. 

An interesting twist to the story: the defendant is also a prosecutor. There are many men already doing years of prison time who were nabbed in stings like this; presumably, none of them are also prosecutors. Is it possible that this particular prosecutor/defendant received special consideration from the judge?

Surely this cannot be the first time the defense has argued that there was no actual child involved. It will be interesting to see if the argument works in other cases.