I can’t go see my brother at his house (a private residence, by the way), under the pretense that we both agree to see each other, without the risk of being handcuffed, arrested and thrown into a police car?

The rest who are on the street don’t want to be videotaped making an arrest.

I meant the lady needed the money because her daughter, who had 3 small children, had been arrested.

:As of July 11, 2019, the Human Rights Law prohibits discrimination in public and private housing based on a favorably resolved arrest record, an adjournment in contemplation of dismissal, a sealed conviction record, or a youthful offender adjudication.

If that doesn't work, you might have to go to the extent of calling the police and having him "trespassed" from the property - meaning that further trespass will subject him to arrest. 

We tell potential tenants that we do not rent to felons, sex offenders, or with any sort of drug or assault arrest even if there is no conviction.

I told this IDIOT I had just gotten off the phone with the Police and they were literally waiting around the corner, to let me know when you show up and that I would have him arrested for mail theft since they abandoned the property under WA law in writing....Then he claimed that I told them I promised them all of their money back.

They don't have enough to send her to a mental institution or arrest her on criminal charges. 

I have denied people with extensive track records because they have repeatedly got arrested for theft, drug sales, assault, domestic violence etc.... 

If the cops are called and the tenant gets a disturbing the peace charge, you have some ammunition, but they generally won’t arrest for that without many, complaints.