Is the lobby open during all advertised business hours or is it shut down at some point be within listed business hours. Particularly in late hours like midnight to 4am?

Yes the lobby is closed early hours

A few customers were "kicked out" of the lobby around midnight recently because the presumable manager wanted to shut it down to have the entire lobby area cleaned I was told. But, by her bitter natured negative/resentful overall attitude I got the feeling there was more to it than that i.e. it would make less work for her shift which brought about the original question since the advertised hours didn't reflect what she was saying.

Yes it is