It's not only misspelled, the way she wrote it means the opposite of what she intended. It damages her credibility to get this easy stuff wrong.
Correctly, it's "lebensunwertes Leben".
More critically, the author completely misunderstands the concept behind the German term.
These people were not viewed as a danger to society or as morally hazardous or unfit.
They were simply the retarded, severely ill, crippled, etc. They were a drain on society's resources, not a moral hazard to it. Getting rid of them was like putting down a sick dog. No animus involved, just practicality.
OTOH, their true enemies (Jews, commies, socialists, Jehovah's Witnesses, Roma, etc.) were a great danger to the moral health of the State. They were evil, not inadequate. In fact, the Jews were dangerous largely because they were so competent. The equally "sub-human" Slavs weren't considered as great an initial priority for extermination precisely because they were incompetent. Or so the Nazis thought.
The two concepts eventually merged to some extent, but initially they were entirely different.