When attorneys get involved Tenants will often concede as the Tenant loses the ability to make vague legal threats that you or I might feel carries weight as we don't know the laws, as well as an attorney but your counsel, shouldn't bat an eye at anything the Tenant threatens.

I think the threat of reporting him to the BAR will be enough to get him to back off.

Private investors are not any help in this arena .. other than they want to steal the property from you.. with the threat of hey your credit is going to be hurt which simply is not the case given the scenario you presented.. 

Cyber stalk us on IG, FB, and here on BP. ;)

I mentioned earlier that the owner had no plan to sell the property, so the threat of walking away from the deal hoping he would come crawling back was slim.

@Bobby Pagliarini from what I understand and this isn’t concrete, the hotel industry has seen AirBnB as a threat to traditional hotels.

IE  insurance if you stop paying.. ( non of that is available in private HML ing) now use the IRS as some sort of threat for more money..  

So just the threat of eviction will get almost anyone out.

While the threat there is real, most proper GCs are not in that market. 

I wouldn't waste too much time or money investing in their threats.