I've owned two of them, can't say I honestly care for the gun. The controls are too small to be effective, especially in an emergency such as the prospective buyer describes. If his wife is 71 and has trouble racking the slide on their existing gun, she will have trouble releasing the safety and / or the slide release on a Hi-Power.
I would suggest a Ruger 10-22 with four 30 round magazines, loaded with CCI Stingers. They're still fairly politically correct, easy to operate, easy to shoot, and while a .22, even with Stingers, isn't an elephant killer, you've got enough fire power to make anybody but King Kong reconsider. IMHO
You must have had some really OLD High Powers. Modern ones come with big (sometimes) ambi safeties and larger magazine release buttons; these can also be retrofitted to older models.
There’s “racking the slide” and there’s racking the slide. If what the guy has is a SIG 229, then yeah, she’s probably going to have problems racking it. Heck, if my hands are even remotely slick, I can have problems racking the slide on some 229s I’ve come across. Likewise most direct blowback pistols. I find the HP very easy to operate, the slide is low effort. And, by the way, you shouldn’t be using the slide release on the HP to load the gun anyway. Rack the slide instead.
Also, there have been several notes of FTS with CCI Stingers of late, even from rifles. I’d recommend something like a Mossberg HS410 before I’d recommend a .22 rifle for home defense.