In Russian language, 'invalid' term is applicable exactly to human beings and means the disabled human. I suppose it might be so in another languages, so there's question if the mentioned book was translated to English from another language.
Similar in general, but different in particularities meanings are typical for the words borrowed from another languages
F.ex.... 'hund' means 'a dog' in Norwegian, but 'hound' means the kind of dog in English
'Speculation' means something like pondering, contemplation, thinking in English, but in Russian it means only the buying something cheaper and sell expensive thus making the profit (it was reason to be jailed in Soviet times BTW :) ).
Origin is obviously the same but the usage survived for one particular meaning.
So for the word 'sympathy' has nothing common in its Russian analog with condolence, compassion - it means only something like attraction, appeal, affection.
And many another words which are borrowed tend to mutate in another languages acquiring slightly deviated meaning. Sometimes in the translated messages I noticed the misusing of such words when the interpreter translated it from English literally and it sounded off in Russian. I guess it might be a case for the discussed example as well.