Picteresq, as owl points out (his post wasn’t up when I posted), that question could be put to R’ Moshe as well. I think the answer is: more mitzvos.
Popa, does a kohen say that brachah when eating terumah? I’m only aware of it for duchaning, and other forms of avodah, but not for achilas terumah.
Even if they did, their achilah might be a mitzvah and a form of avodah, but nashim va’avadim would be a r’shus.