I guess the idea is that you're "blind" to the brand, origin etc of the egg. You don't know anything about it other than what's directly in front of you.

Although now you bring it up,it would be interesting to see whether actually blindfolded taste tests would confirm or deny your idea that the visible quality of the yolk correlates with it's (non-visible) taste.

The meaning "blind" being used here is: https://en.m.wikipedia.org/wiki/Blinded_experiment

It has nothing to to with depriving a participant of their sense of sight (except incidentally.)