exactly, this guy is going to be a PITA no matter what, he's just looking for shit to be upset about.
I would find some subtle ways to scare this guy without actually threatening him. Learn a little Russian and when you are outside and sure he's eavesdropping, act like you just made a call, then loudly speak in Russian and end the call with 'make it happen'...Mad dog this guy when you see him, don't break eye contact till he does first. Smirk a lot.....
Oh I could so do this as I belong to a WWI Russian reenactment group that belong to the GWA. The Legion Russe