"..was far less than the 1000 feet and 5 miles which I understand is the minimum.."
That may be your problem right there, it's either/or, not and.
I've had pilots query whether converging traffic is 1000' above or below, there's no way that SLF would be able to accurately judge while sitting in the back.
DtA, with all respect, members of the public believing that "they know what they are talking about" simply adds to what is a very stressful environment. I was on the desk once when an irate SLF called in to complain that they had to go around because of a firetruck on the runway. After investigation, it emerged that the pilot elected to go around because of an unstable approach off a visual, the firetruck was waiting at the hold to do an inspection!
'69