I have had plenty of run-ins with local plumbing inspectors. Often local inspectors will have a I like code. These are codes that are not present in the local jurisdiction having authority codebook. I ran into this many times working in Chicago as the state of Illinois has codes that differ in every city, in every county. It is impossible to know the local code unless you contact City Hall and get a copy of the amendment from the state plumbing code. It sounds to me like your plumbing inspector has a I’d like it this way code. As a plumber for 30+ years I have contacted the head plumbing inspector for the state when I run into these matters. This sometimes results in backlash from the local plumbing inspector who thinks he is the plumbing God and wants to write codes the way he sees fit. Connecting PVC pipe to ABS pipe using transition glue is definitely a plumbing inspector creating his own codes. I called these Home Depot plumbers. Often the material purchased at Home Depot is not approved material for the state. I can give you many examples such as PVC fittings that do not have the approved ANSI stamp, incorrect schedule or transition glue is another good example. Copper fittings should also be stamped but often Home Depot has unstamped Chinese copper fittings of the incorrect schedule. Don’t even get me started on shark bite adapters.