It is not unsafe but I would still call it wrong and change it.I've seen electricians do lots of things that worked but I would still say they were wrong i.e.- not the standard. ( Distribution panels always come to mind)In this case there is no good reason to leave it wired the way it is now. Assuming it's all on one breaker. It is a confused mess and unnecessary. He is changing them out . He should use the standard electrical way of wiring them. It will also save him from buying another gfci. Those pennies add up over a lifetime of house maintenance. If any electrician tried to wire it the old way at your house would you say, " Hey, why not, it's pointless, going to cost me more and add needless ,confusing wiring but what the heck--go ahead." My brother once needed a new ceiling fan put in his house. The box had multiple switches and a nightmare of wiring. It worked but took a while to figure it out. I just disconnected it and rewired it correctly so it was standard. I had a few wirenuts and lots of small pieces of wire on the floor when I was done. Just me maybe......lots of people would just hook it back the same I'm sure. Jim C.