No, it's not 2 years either. That's not the detection window. It's the lenght of the drinking habit that the test works for (i.e. long drinking habit). It's not used to test for a single consumption. If you cared to read what you're quoting, you'd have known that.
It matters that it's the hair, because hair tests aren't used in antidoping. Who cares if something can linger in the hair for 2 years (which you haven't proven) if it doesn't in the blood and urine which are all you test for? See what I did there?
I'll give you 6/10 for the trolling, you got boring top quickly. Have a nice day.