Tom Griderson's 'reasoning' is nothing more than anti-Muggle prejudice, pure and simple. Anti-Muggle spite. He thinks they're nothing but animals, and so he's classified this in his mind as nothing-to-do-with-us-real-people. It's criminal that he's a supervisor in that department, although given this regime, not surprising.

Norma Brownmiller, on the other hand, deals more with facts and figures. She has a background in statistics--quite the whiz in Arithmancy--with a strong interest in public health. She actually studied at St Mungo's for awhile, but ended up not getting her Healer's certificate, and ended up in the Ministry instead. I'd listen to her instead.