Your buddy has a bunch of issues going on here...
but if money is tight, preventing training on a reasonably consistent basis ....I think it makes the choice of a semi-auto shotgun vs a pump a moot point. They both require some training...she has to get the safety off, have some ability to deal with recoil, etc... / so without training, in my view they're both equally poor choices - even though there might be pluses or minuses for each platform in the hands of a trained shooter...the real issue here is training / or lack of it.
To say one is less poor than the others - is a strech in my view.
Spending time with someone dry firing essentially....is ok / but its not a replacement for range time - and actually firing the weapon.
Length of pull, weight of the gun, what gague, managing recoil, balance of the gun, proper sight picture, etc ....all affect how a shotgun fits the shooter...let alone the effectiveness of the weapon in a defense situation ....and what fits me at 6'5" and 290 lbs vs my wife at 5' 9" and 115 lbs ...is way different !!
If your buddy thinks he needs a tactical shotgun - he should probably buy what fits him ....and as his budget permits, hopefully get some range time for his wife, if she wants to shoot, then let her pick what she wants for a defensive firearm.
I don't subscribe to the attitude that everyone needs a tactical shotgun ...although I don't dispute they can be effective defensive weapons. Even a shotgun with a 28" barrel - can be used for Defense...although it may not be a "tactical - fighting shotgun" ...its fine for Defense. I might pick a semi-auto over a pump gun ...or even an Over Under...and if I train with it....it'll be fine.
For somebody that doesn't train much ...even a good revolver is a better choice than a lot of weapons / certainly simple to use and fire - vs any shotgun where you'll have to remember to manipulate the safety, etc. before you fire it....