No, that wasn't a stalemate line. It was extremely close to one, but it required a correct guess every turn to hold Mun/Ber.
England's units in Lvn and Pie had the ability to cut Tyo and Pru, and Bal/Bur could cut Mun/Ber respectively, so the only units which could issue an uncuttable support hold were Bohemia and Silesia. England had 3 units on Munich and 2 units on Berlin (one unit, Kiel, was on both and had to choose which to help the attack on each phase).
This meant that for a true stalemate, you'd need 2 units support holding Munich, and one unit support holding Berlin. Turkey did not have enough uncuttable units to do that - he could *either* issue 2 support holds to Munich, or 1 to Munich and 1 to Berlin. This meant that Ber & Mun could be held by correctly guessing the opposing moves, but could not be held indefinitely. If Turkey ordered both units to support Munich and England attacked Berlin with 2, or if Turkey ordered Silesia to support hold Berlin and England attacked Munich with 3, England would win the game.