I'll let others comment on the spiritual matter of someone who would kill their own dog for that reason and in that way...
The woman was concerned the dog may be too aggressive and unstable to be passed off to another person, except apparently trusted this 1 shelter.
I don’t remember how old Bela is, but he looks elder. That may have factored into it, too.
I know I had a demon cat whom I decided was not worth “selling” or otherwise passing off to a particular person. I could not bear that on my conscience; she was that evil. So we gladly sent her to the standard shelter. If someone foolishly picked her up, so be it. Otherwise, she would’ve been euthanized. So be it. Better for her and everyone else.
From the articles I read on the situation, the woman feared that the dog may be adopted into a family with young kids etc and she didn’t trust Bela’s behavior. Having large, breed dogs over the years.. there is a different “fear” if a larger dog is adopted. For one thing, you don’t ever want them to be used as a fighting dog. You may not want a newbie to the breed decide on a whim that a Doberman/GSD/Rott would be a great addition without prior knowledge or experience either. The owner decided the dog was to live out her life in a sanctuary or be euthanized as a means of preventing injury/harm to others or her dog. I can only imagine she loved the dog or she wouldn’t have gone to the trouble of expressing her wishes in her will. IMHO.