They probably take it for granted (as everyone should) that euthanasia = murder, and therefore (as they see it) this term is not a euphemism. It’s just a name for a particular kind of murder, like infanticide or, shall we say, iatrogenic homicide.
Nut now the grandchildren of these heroic doctors are voluntarily murdering the untermenschen, the disabled, the elderly, babies born and unborn--- and congratulating themselves for being so enlightened, humane, and progressive.
Who won WWII? Really? Who won?