Edu- I skipped through- 1) it says that not all (Including Rav Ovadia Yosef) accept this as a "custom" and 2) more importantly this is not the topic lechathila. It is not even about Kashering it, its about having it go back and forth from meat to dairy w/e going through the Kashering process as it is explained that it does not absorb to begin with, thus their is no fear or chance of mixing meat with dairy or even kosher with non-kosher.