> I find it easy to imagine him not recognizing his employee who had a fairly average build, in a fairly common outfit, in an elevator with people being conditioned to keep as much distance as possible

I find it hard to imagine to be honest. If they tracked him down because he bought the Taser and other items, but don't have a clear ID from the CCTV and DNA, it's possible that the assistant hired someone for the dirty job and provided him with the tools?