You are certainly right, the further the Greeks push against the Ottomans, the more push back they will get. Not just from the Ottomans, but also from the Bulgarians and the Russians as their competing claims will make them adversaries real quick, especially if they come close to Constantinople. Greece does not have the capacity to conquer all of Anatolia and restore the Byzantine Empire, despite my not so subtle interest in doing so. It simply doesn't have the people, nor the will necessary to completely subdue the Turks. If they tried to do it anyway, it would likely end in disaster for all involved as sectarianism and terrorism destroy Greece. Nevertheless, Greece is stronger and wealthier ITTL, which will enable it to push further than it reasonably should.
This quote confirms my suspicion that Greece will push as far as it can, not as far as it should. Even if they are capable of pushing the border further north than the population on the ground justify, and annexing parts of western Anatolia, or taking Constantinople in spite of Russian wishes, does not make it a good idea.
At least once in this timeline, and probably more than that, the Greeks will bite off more than they can chew. How dire the consequences are, or if losses are permanent, will depend on the direction history takes, but Greece will probably take a black eye or two during the 19th and 20th centuries.