Yikes! He didn't pull the knob and tube???
Nope. Still got it all over the place.
In fairness it's possible (although unlikely, given this particular person's spending habits) that she told the electrician to just do part of a job. It just seems unlikely that any electrician worth his salt would leave knob and tube and just connect to it.
I know that it's safe as long as you don't overload it. It's been there since, well, since knob and tube was what was available and hasn't caused any problems yet. Most of it powers nothing more than a few light bulbs, although it was interesting when I ran an 8000BTU air conditioning from a knob-and-tube powered socket. It wasn't very long before I dug out my 20A-rated extension cable and plugged it into something a little more - er - capable.
When it cools down my project is to rip out lath-and-plaster walls, replace the knob and tube wiring, and rebuild. That should keep me out of trouble for a while.