As we saw in his first appearance, Zephyr is capable of not acting like an obnoxious pillock all the time.
Deep inside, he knows he’s got no real chance with RD, so he does his flirting as obnoxiously and ridiculously as possible. That accomplishes two things.
One, it still lets RD know how he feels.
And two, since he’s fully aware that she’ll never go for his ridiculous posturing, it lets her know how he feels without setting himself up for any kind of real rejection.