Lot of questions in there.
I am convinced they have exceptional night vision. I don't think that comes at the expense of color vision. The reason is simple, the sheer size of the eyes. If their rods and cones are packed as densely as ours and their eyes are much bigger, then they would have many more of both. The bigger the eyes are, the less necessary a tradeoff becomes. Geometry meets biology.
I don't, however, know that they have color vision. I assume so, but it is an assumption, not knowledge, not experience. I do know that something very very heavy with a long stride walking around out there on 2 feet in the dark has night vision far beyond mine. That I've experienced.
Consider the possibility they can tell whether fruit is ripe by smell, not sight. I went for a drive Friday night and I could smell the huckleberries when I rolled the windows down. My nose isn't particularly good. Too many household chemicals. I bet they can tell better than I can just by smell. There could be other things ... if they're familiar with the kind of fruit, then perhaps the surface reflectiveness changes, something they could see without color vision. Talk to a person who is colorblind and find out what their visual cues are.
I'm not sure your question about bright colors is in the context Paulides intended. I do avoid bright colors now even more than I used to. There is a second component to many of the cases Paulides mentions bright colors in which you seem to omit: the unexpected appearance of bad weather immediately following the disappearance which interferes with the search. This, at least as inferred by Paulides, seems to imply one of two things: either whatever is doing the abduction can control the weather or whatever is doing the abducting has better forecasting ability than we do ... or at least than we did at the time of the incident since many are older cases.
Regarding bright colors, I do not worry about their visibility from ground level, I worry about their visibility from above. The day my compass and GPS both went wonky and would not settle on North, I was ... concerned.
MIB
edit / adding addendum - for more about weather, look at the North America and Beyond volume in the index under "bad weather".