The thing is, by not ever fielding those questions -- by actively discouraging them, by calling them misogynistic or transphobic or hateful, you're silencing the discourse. The conversation ends. No one learns anything. The person who is so focused on your genital surgery hasn't suddenly become less immature, less biased, or less ignorant. The world keeps turning, but that person stays the same.
It is a sad thing that a lot of the questions thrown at trans women shift towards what happened to their dick, if they opted for surgery. It's tied up in misogyny, it's also tied up in patriarchy (why ever would you throw away the penis, reigning king of the genitals in human history? etc.), and it's horrible. But I don't think every person who ever asks you a question about it is doing so with an agenda.
MUCH of my life when conversing with straight people after telling them I'm gay has been spent dispelling notions and ideas of what they think gay love is like, what they think gay sex is like. But I'm not a sex negative person. If someone wants to know if I've sucked an 8'' dick, I'll tell them so. It's not invasive. It's a dumb question, but I don't care. But I'm not going to stop with just my answer. I will follow it up with, "why do you care so much about my sex life? Why does it matter?" And a good discourse can start from there. I've helped straight people change their attitude towards gay men and divorce the notion that the only reason we're gay is because gay sex is awesome. Being gay, hell, *sexuality* in general is so much more than what goes where or how <insert sexual act> works.
Laverne is right in that focusing trans* discussion on sex reassignment, particularly of trans women, objectifies them. She is, however, perpetuating a common trope in the trans* community by completely never ever talking about that issue. It's not a universal one in the trans* community, many don't ever go through the process. But the ones that do can only help the movement by being willing to talk about it to some degree, even to a random reporter, by acknowledging context.
The conversation is never going to come off as anything more than radio silence if you're unwilling to broach the subject. Would the gay movement have come as far if we completely shut off our private lives from everyone else? One of the things I enjoy about being gay + meeting other gay people is that there is an openness about what sex is and that there's no shame in it, no matter what you're doing.