Women, men, or polar bears… People want what they want. But when they actually get what they want? Wow, that feels good!
You could probably make the argument that the harder something is to get, the better that "wow" feeling becomes.
Thus, in a society that has historically shunned public expressions of homosexual sensual expression, seeing two women of otherwise-perceived heterosexual orientation kiss can seem especially exotic and thrilling to the average heterosexual male.