Plural of adam would be adamlar, people is generally "insan" or "halk" and I can't work anything the first part might be so I think this is a direct reference to the mayor.
What you're suggesting would be something like "Türkinsanı".
Nope. The initial argument is correct, "Erik Adam" translates literally to "Plum Man". However, TKNYADAMS as a whole doesn't make any sense in Turkish. It is literally TK (Turkish Airlines airline code) + NY (the city) + ADAMS (the mayor).