WM standpipes are often glued , so cutting is easy; but putting it back together is also easy, so I don't understand why he didn't.
I don't know what source you used on the internet to find a plumber; but on internet sites like **** I tend to assume that a lot of the "stars" and such are bogus.
Even a sight like this....you don't know me from Adam! I could be making this all up! Now, if you follow a forum for a while you get to realize that most of the responders here DO in fact offer good advice. At least it's free, and we don't make a mess in your kitchen!