It is ignorance, not stupidity. But it is ignorance without any desire for knowledge.
No. There is no way that he could have said what he said in response to my post out of any sort of ignorance. He doesn't even seem to have any ability to comprehend a word he reads. Ignorance would have asked questions and sought clarification and understanding. Instead, he derides the content of a post he doesn't understand and insults it's author as if I'm the one who's ignorant.
Only raw, undiluted stupidity can account for his comments.