How to deal with a wealthy co-signer parent that is a financial bully

[Adam Christopher Zaleski]

I had a tenant for two months. They got evicted for not paying rent and eventually left, but on their own terms. It's a 20-year old rich kid that has zero accountability. His dad is very wealthy and is a bully

His son left owing 18 days of rent, cleaning fee, late fees and some lawn maintenance fees because he didn't mow the lawn for 30 days and mowing the lawn was part of the lease. 

The dad wants a full deposit return minus the cleaning fee, which is not even connected to reality. He also mentioned that he thinks there is a gas leak in the rental unit and his son had to go to the doctor twice to get treated for head aches. This is a totally made up story. It never happened. I interpret this as a threat and intimidation. I have all the documentation needed to show that he gets zero deposit back and still owes an extra $1500. 

All deposit disputes are handled in small claims court in my state, no exceptions. If we go to small claims court, I win. He doesn't have a chance. As a result, I think he is going to try alternative methods. I am expecting a threatening letter from a lawyer in 1-2 weeks. Any ideas or suggestions on how to handle bullies?