The person writing the article really dislikes the idea of Turkish nationalism to the point of calling any nationalist voice as supremacists, which is a dumb take when both parties mentioned (IYI and ZP) follow Ataturk's nationalism idea. (Your ethnicity does not matter, being able to say you're a Turk is important)

Nationalist views do not weaken CHP, they improve its strength to attract voters. There's a reason why on all polls Mansur Yavas overtakes even Ekrem Imamoglu's votes against Erdogan, even though he announced he was not planning to be a candidate.