DY: Besalel is not wrong in that there are Ma’amarei Chazal that are against only learning without performance of Mitzvos (and Ben Levi apparently doesn’t know what the word “Medrash” means). He is wrong in his application of those. As far as I know, every such statement refers to someone who only learns and therefore doesn’t even do Mitzvos.
646 is correct that there are several Mitzvos that are weighed K’negged Kol Hamitzvos. He is wrong in assuming it’s just a turn of phrase. We take all of them literally.