From the little bit I have seen of the PT22's at our local Academy Sports, I do not think they have the same family relationship with the Beretta Bobcat / Tomcat, that the larger Tauri have with the 92/96 series. The Beretta's are DA/SA and I believe the Taurus is DAO
While it is true that the tip up barrel does not require an initial slide rack on the Bobcat or Tomcat, you can't clear a jam without racking the slide, and on the Bobcat or Tomcat, it's not that hard to actually pop the slide off the frame when you're diddling with it. If anything, it's actually rather common, adding an extra layer of complication to operating the gun that may not be readily apparent. I don't know if this holds true for the Taurus, but it's worth looking at.
So, in other words, to state the obvious, you want something that won't jam and leave her holding a slide in one hand, and a frame in the other. I often pocket carry a Tomcat, and sometimes in summer, a Bobcat, so I am pretty familiar with these two little guns, and how they work and won't work. The Bobcat is dead on reliable with high quality ammo like Mini Mags and it's easy to be a crack shot with it. The Tomcat is one hundred per cent reliable with any quality FMJ or HP rounds that I have put through it.
I like Taurus guns and have a bunch of them, but I would also strongly suggest that if you are going to use of these little guys as a carry weapon, you get the best of the litter, and that you seek out a shop that has the little Beretta's. If this is the type of weapon she has to carry, I really think your best solution is one of the little Beretta's. You can depend on them.
Of the two, I would suggest the Tomcat, but it's bulkier and beefier than the Bobcat, which may not be that apparent just from looking at pictures of the guns. There is also a bullet weight limitation on the Tomcat because of the possibility of frame cracking, which I ignore for carry ammo, as I consider it expendable.