Tony, here's the response I eventually got:
That is a loaded text. It could be what he is suggesting, but I kind of doubt it. My initial thought was that it’s blocked further down the line, or the piece of pipe directly connected to the sink (pop up assembly) is clogged. Maybe ask him if he took that stopper out and looked directly down the drain. A lot of times this can be remedied by removing the stopper and making a hook on a clothes hanger and pulling out the hair.