Haber also invented the Haber process and on the whole probably saved an order of magnitude more lives than were lost to his inventions.
With that said, I think it's appropriate to focus on Clara's life in this discussion.
The programme was called "Brot aus Luft" (Bread from air). The process still uses 1-2% if the worlds energy today.
This is not a very good defense. He could very well have chosen not to develop those weapons. He made a conscious decision to kill lots of people, and we can and should absolutely judge him for this, independent of anything else he's done. We don't give surgeons a quota of one free murder for every ten lives saved either.
(Edit: As always, I'd be interested in constructive criticism from the downvoters.)
I wonder how her family got that name? Many family names seem to originate in professions. What did you need to do to get Immerwahr?
https://www.goodreads.com/book/show/40121985-how-to-hide-an-...