Dear Yosef,

The Rashash is not answering the contradiction to Rashi from the Mishnah in Terumos 7:2. He is answering another point. The Pasuk v'Chol Zar Lo Yochal Bo is the source for Terumos 7:2 to exclude a born Kohenes from paying Chomesh. Yet our Gemara Yevamos 68a includes a born Kohenes married to a Yisrael in the prohibition of a Zar eating Terumah from the same Pasuk! It therefore seems that the Mishnah in Terumos and our Gemara are two different opinions.

The Rashash answers that based on what he wrote in Kesuvos 34a there is no contradiction. He brings there many sources that the same Pasuk can have simultaniously both a simple meaning and a Drashah meaning. So it's not a contradiction to include a Kohenes in the prohibition but with the same Pasuk to exclude her from Chomesh.

All the best,

Reuven Weiner