Much of what the article says makes sense, however there are a few things which it said which make me suspicious. As far as I can work out, the sun does not know when it is cloudy or sunny down here. As a result there is no reason for the UV light to be stronger or more intense on cloudy days than on sunny days. The UV light reaching the edge of our atmosphere will be exactly the same. The difference is that the UV light penetrates the cloud cover better than electromagnetic radiation with a longer wavelength. As a result colours on a cloudy day seem duller to us. The only reason a fluorescent lure will look especially bright is because everything else is duller than usual.
What the article says about colour loss at depth is correct. There are a couple of ways to get around that issue though. A fluorescent material is one which absorbs UV light and emits light of another frequency. UV light penetrates to a greater depth than any light visible to humans. A fluorescent yellow lure will still show up as yellow at a great depth due to the penetrating ability of UV radiation, because it absorbs UV light and then emits yellow light. At a great depth, but where UV light is still present a fluorescent lure will appear to glow.
Let me know if I have gone wrong somewhere but this is what logic is telling me.
A very interesting article though
