Was his wife ill? Are we talking physical pain here?
Anyway, helim down’t make you happy. Just gives your ghost a squeaky voice.
I wondered that. As far as I could tell, the answer is no. Some of the accounts I read indicate that it was the man who was the driving force here, so this expression of his would in that case be a mere instrument of his domination. That's what I'm picturing.
As to Helium, I believe it is its inert nature which gives it its benign properties here. The body reacts to excessive CO2, but not to the displacement of O2, apparently. The same goes for nitrogen gas,N2, which of course is the dominant constituent of the air we breathe. There have been deaths due to N2 asphyxiation, and I believe the insidious nature of this hazard is the lack of warning before blackout.
Helium is a scarce resource, so one would think that N2 would be the considerate choice for this purpose.