Yes, unfortunately it is. His All Holiness aways tries to change this outrageous requirement. One of the variants is to give a freedom in election of the Patriarch and then to grant Turkish citizenship to the winner, who could have any citizenship prior to the election.
Historically, in 1948 late Patriarch Athenagoras, one of the greatest Orthodox Hierarchs of XX century, was elected to the office of the Patriarch being an American citizen and then received Turkish Citizenship. After that, late Patriarch Dimitrios (died in 1991) and current Patriarch Bartholomew were elected from the list, which included only citizens of Turkey. Moreover, in 1972, after the death of Patriarch Athenagoras and prior to elections of his successor, the government officials excluded several very respected key candidates from the list, even while they all hold citizenship of Turkey.