NATO is an alliance expressly aimed at strengthening member states' national security. Turkey has been a member for decades while Finland and Sweden now want to be in. If Finland and Sweden are actually supporting Kurdish independence fighters using violent means, I don't think it is strange at all for Turkey to demand concessions before they can enter NATO. And I also think it is ridiculous for Swedish foreign policy to be hijacked by one Kurdish MP who apparently holds a massive amount of power.
Yeah I actually agree with this. No love for Erdogran, but the PKK are terrorists and if Sweden is turning a blind eye to them that deserves a response.