Maybe Erdogan sees the downsides of continuing NATO expansion. From Scott Ritter at consortiumnews.com:
In opposing the application of Finland and Sweden, Erdogan has disrupted the military alliance’s effort to further provoke Russia with even more expansion.

Letters of application to NATO from Finland and Sweden, presented to Secretary General Jens Stoltenberg on May 18. (NATO)
On May 18, the secretary general of the North Atlantic Treaty Organization, a Norwegian named Jen Stoltenberg, stood on a stage, flanked by the ambassadors to NATO of Finland and Sweden, Klaus Korhonen and Axel Wernhoff, respectively.
It was one of those made-for-television moments that politicians dream of — a time of high drama, where the ostensible forces of good are faced off against the relentless assault of evil, which necessitates the intervention of like-minded friends and allies to help tip the scales of geopolitical justice toward those who embrace liberty over tyranny.
“This is a good day,” Jen Stoltenberg announced, “at a critical moment for our security.”
Left unsaid was the harsh reality that hundreds of miles to the east the military forces of Russia and Ukraine were locked in deadly combat on Ukrainian soil. Also left unsaid was the role played by NATO in facilitating that conflict.