Turbos can spin upwards of 100,000 rpm, so even a slight imbalance on either side of the shaft can wreak havoc with the bearing it rides in.

You'll know the bearing's gone bad because your oil consumption will go up and you'll start seeing more blue smoke in the exhaust, as they usually fail on that side.

I agree- get it in writing that they chipped the compressor wheel during reassembly, and any subsequent repairs required due to turbo failure they will cover. If they won't put it in writing, maybe have your attorney give the shop owner a friendly call. . . and keep note of this thread's topic/number, so it can be used as back-up if you get into a "situation".