I went and searched how to block someone from making comments on your posts. There is (was) a way, that seemed quite simple and straight forward, under privacy settings, but when I went to my settings, the interface did not look at all like what was described. I called DH over and he couldn't find what we needed, either.
I suspect that the instructions were written before the "new" look of Facebook.
Oh well, I will have to get better at ignoring.