Responsa על שבת 266:4

That which you have written, namely, that you treat as forbidden wine that has been touched by a Jew who publicly desecrates Shabbat as he is an apostate against the entire Torah, proving this assertion from Responsa Mabit as cited in Nekudot Ha-kesef on Yoreh De’ah (124:2), which forbids the drinking of wine touched by Karaites as they desecrate the festivals, which makes them tantamount to Shabbat desecrators—indeed, there is someone who disputes this, and you therefore ask me for my opinion in this matter.