Isn’t it obvious that the unusual term “d’var mitzvah gemurah” is different than “makom mitzva”???</em.
Not really, he just means as opposed to other types of food for Shabbos which are not necessarily considered a mitzvah.
“You used the term in response to MeemaYehudis, who asked the shaila”
Yes, so???
In that context, I assumed you meant “chumra” the way it’s commonly used, not the way iy’s used in nosei keilim.