I’m impressed to see the thoughtfulness of your response; not just correcting but and especially differentiating an “extreme” from “extremist”. I think it’s also helpful to differentiate the sentiment. One is an extremist position, the other is opposite. If you need more emphatic language the other is polar opposite. It can sound extremely far away (true without characterizing), or emphatically so (true without using words like “radically different” which are true but also emotionally misleading).