Bathtub drain replacement

I have a fitted bath/shower, no access panel to the drain. The visible flange on the drain is corroded and unsightly. I had a plumber out to my house for a leak elsewhere, and asked him if he could replace the drain. He said no, it was not possible, because without cutting a hole in my kitchen ceiling, he could not guarantee that the shoe fitting would not drop and he would be unable to screw in the new drain and stopper assembly.

Question -- was he full of it? It seems to me that if this were a common problem, someone would have invented a handy tool which would allow the shoe fitting to be held close while the new drain was installed. If they haven't then maybe this is an opportunity for someone.