Ok so I was at a friend's house today helping him fix his furnace. Shortly after we fixed it I was in his living room watching TV when someone came to the door; I decided to open it, since my friend was in the shower. It was some guy dropping off a package for my friend; he gave it to me and left. My friend came out the bathroom shortly thereafter and this happened
me: ayo some redhead dropped this off for you
him: a chick?
me: no, some redhead dude
him: but you said "a redhead" thus insinuating it was a chick
me: uhhh redhead is gender neutral
him: no, it's fucking not

I am under the impression that "redhead" can be gender neutral, as displayed by my statement. Whereas "some blonde" would clearly be a reference to a female because I'm under the impression you don't call dudes "blondes." You just say "some dude...yea with blonde hair."
QUESTION: is my understanding of white culture and etiquette correct, or is "redhead" a term only used when referencing a woman?