The conclusion that your childens' stated preference is based on color alone is non-sequitur, at best. At worst, it's a blatant red herring.
Except for the minor fact that they said so themselves. Here's the quote again for your benefit "they describe it as artificially yellow".
I also gave evidence that this has happened before, when we transitioned from gas light to incandescent light. Lastly even today people prefer the somewhat whiter hue of halogen over regular incandescent yellow, indicating that the present yellow isn't really all that is made to be.
Now, and here's something you don't seem to be aware of, constructing an argument is different than a logical proof. E.g. "he had a gun, motive and opportunity. He was at the scene of the crime and was seen running away after shoots were fired". It does not logically follow that the person did the crime and it would be a logical fallacy to state as much, yet it is the reasonable and logical conclusion nonetheless.