An original source, not a diyuk in what someone else thought. In addition I’m not questioning if it is heresy (You don’t need this Rabbi Shapiro you have the Raavid), rather if any accepted rishon espoused that view.
If you look at the Raavid (aside the fact that it is unclear if he is going on baal temunah or guf), he says bemachshava zu. It is an interesting lashon. It likely means that there were some great people who believed in machshavah that one can refer in machshava to Hashem in the language of Guf and baal Temunah. The Raavid then brings pesukim, which refer to Hashem in that way. The Raavid however, seems to agree with the Rambam’s prime theology. The question then remains what does he do with the pesukim. Therefore, it is logical that the Raavid is arguing that since the Torah uses the leshonos of guf and since there were gedolim who went with a machshava of thinking about Hashem in that fasion, one can therefore not call a person who mistakenly says Hashem actually has a body (Like Sam2 claims Rashi believes, chalilah) is a Min.