[Blood of Tyrants]

There were two possible motives, 1, Rush's house keeper was attempting to blackmail him and was unsuccessful or 2, (more likely) this couple is in trouble with the law and copped a deal to help the police bust Rush Limbaugh (why else would she wear a wire in conversations with Rush?) in exchange for a reduction in or dropping of charges. She then decided that she could make a quick buck with the Enquirer.

[steve50]

this couple is in trouble with the law and copped a deal to help the police bust Rush Limbaugh

Informants are used all the time, most are criminals and many are even paid for their efforts. Never heard a conservative complain about using them to bust other users before.