If the manufacturer says that a fly-by is not advisable, then so be it.
Not sure that some guy who’s not a pilot or an engineer with a pair of binoculars looking at the underside of my 130T jet in the dark moving at 150 knots is going to be able to add much useful information.
Dark is a fair point. But otherwise; even a non-pilot could say "I can see three legs sticking down". Or more importantly: "I can only see the front leg and one of the back legs". Or, "One of the landing legs is at an angle".
“They look like they’re down from here”. How that gonna change what you do?
It won't, but if they said "I can only see two legs hanging down", you would at least know what to expect, and which way the aircraft will fall.