Paul loves his fellow Jewish people and his heritage in Judaism. The thought that his words, "not all Israel are Israel" would be used as antisemitic tropes against Jews & Israel would devastate the Apostle because they are completely abusing his point. Those who do this are doing exactly what

Peter warns us about these people in 2 Peter 3:15-16 - "Bear in mind that the patience of our Lord means salvation—just as our dearly loved brother Paul also wrote to you with the wisdom given to him. 16 He speaks about these matters in all of his letters. Some things in them are hard to understand, which the ignorant and unstable twist (as they also do with the rest of the Scriptures)—to their own destruction."

https://www.restorationmessiah.com/media/j2hfvh4/romans-26-9-1-13-paul-s-love-responsibility-toward-the-jews