Well, answer posts are supposed to actually answer the question.
As you say yourself, it couldn't be clearer what the question is: it's "Have light gases like hydrogen or helium been explored for ion propulsion?" I think that your first answer post is inappropriate because it does not answer that question, and I think that's why that post was ...
The question couldn't be clearer
The title reads
Have light gases like hydrogen or helium been explored for ion propulsion?
and in the body the question is repeated:
Has the "ion sorcery" for light gases like hydrogen and helium been explored experimentally for future ion propulsion technology? What about neon at least?
These are the only ...
Looking at that one specifically, it is very obvious you didn't like Bob's answer, despite it being accurate (he wrote Yes, along with info as to why it wasn't used), and wrote a bit of an attack on him in your post without providing anything useful in an answer. You basically said "Yes, but I don't like the way Bob wrote it"
Oh, and then you also ...