NATO doesn't have multiple tracks - a member is a member. The US and their allies understood very well what that meant when they accepted those new members. NATO is about retaliation after external (and generally accepted to mean Russian, in practice) attack, or it isn't at all.

This is not a case of Turkey whining about a few kurds blowing up a few police stations, this is the raison d'etre for the whole thing. Renouncing NATO duties would be the worst loss of dignity the US ever experienced, and would jeopardize its richest partner market, with uncalcolable losses.