He said "Betty thinks" before that comment. Rather misleading on your part, I would say.
"To “steel to” a task is to prepare to do it. His anger, he feels, is happening to keep ahead of an ‘explosion’."
I take his comment just the opposite that he had to keep his thoughts off of sex to stay whatever his interpretation of "pure" was.
It is sad to see you altering this. Another example of how language and history can be manipulated to one's perspective which does not have to have anything to do with reality.