Let's get this straight (pun so very much intended)
I'm going to preface this by pointing out that you are a vocal, self-identified conservative, and I am a vocal, self-identified liberal, so we are going to disagree on certain key points without much chance of ever seeing eye-to-eye. So I'm not going to try to convince you of anything, and I'd appreciate your doing me the same courtesy.
With that said, please don't patronise me. I'm a professional writer, a trained storyteller and a rather competent linguist, so please take me at my word when I say I'm quite aware of the subtext of my work, and I don't appreciate the implication that I don't actually know what I wrote.
So your issue seems to be that, by using the word "heterosexual" twice in a particular context, I am "problematising hereosexuality". Frankly I'm not sure whether to respond academically, or from the standpoint of being a straight woman with a very satisfying sex life, but since I've written about my own sexuality in other forums I'll stick to the academic.
Disney has a long history not of "problematising" homosexuality, but of effectively effacing it. This comes from a long-ago decision by Walt himself to appeal to the broadest possible demographic, and if you want to know more about that you can read it on my tumblr. At the time it was a perfectly rational decision and one that certainly played a role in Disney's early near-monopoly on the family entertainment market, but times have most certainly changed. Homosexuality is increasingly de-stigmatised, and positive adult non-heterosexual role models are beginning to be visible in mainstream media. "Orange is the New Black", for example, has received much justified praise for placing gay/lesbian, transgender, multi-racial and lower-class narratives on the same footing as the narrative of white, upper-class Piper. It isn't about overpowering or replacing heterosexual narratives: it's about increasing the number of non-heterosexual narratives to match. Equality, not subjugation.
In children/family entertainment, those role models don't exist, and this is a problem because there is an irrefutable correlation between exposure to positive relatable role models as a child and mental health (of the I-don't-hate-myself variety) as an adolescent. It's like the theory that the characters in Winnie-the-Pooh are stand-ins for different mental health issues: a child with no knowledge of depression can still tell a parent they feel like Eeyore. A young adolescent struggling with his/her sexuality benefits enormously from positive portrayals of the full spectrum as a child, because even if the adolescent in question ultimately determines that s/he is straight, that decision can come from an unbiased and egalitarian understanding of all the possibilities.
Disney is the world's largest provider of family entertainment - more than that, Disney has (until recently) been the textbook in the question of what and what "isn't" appropriate for family entertainment. That means that if a child were to reach into a barrel of DVDs of animated movies and pick one at random (discounting the collected works of Ralph Bakshi because let's not be idiots about this), that child would have literally no chance of picking one with a protagonist who isn't a zero-on-the-Kinsey-scale heterosexual. Heterosexuality isn't a problem, but that is. Heterosexuality isn't just the norm in animated entertainment - it's the only. And the two times in my "Frozen" essay that I use the word "heterosexual" are, in fact, to point out that that is the case. In the first, I qualify that my table of "happily-ever-afters" only includes heterosexual relationships because those are the only ones available to include. In the second, I draw attention to the fact that certain "Frozen" fans use Elsa's lack of any relationship as indication that she is a lesbian, and I rather lament the fact that that seems to be the best Disney has to offer its LGBTQ fans.
So it's really a stretch to say that I'm "problematising heterosexuality". A feet-behind-the-ears, Cirque du Soleil contortionist stretch, if I'm honest, because at best I'm not really saying anything about it. I'm saying that it's a sad, sad situation that the largest provider of family entertainment in the role has such a dearth of positive role models for LGBTQ families and children that even a slight deviation from the established and *very* heterosexual Disney model is lauded as a breakthrough. On an entirely personal level, I have absolutely no issue with heterosexuality, though it would probably say something about my self-esteem if I did. I do have an issue with non-heterosexual individuals not being able to enjoy the same ability to relate to beloved characters that I do. It's not fair, and frankly it's bullshit. Pointing out - twice - that the Disney model is exclusively heterosexual isn't "problematising" anything except the fact that it's exclusive.
Now, if I'm still complaining about heterosexual narratives when there's actual equality in media, feel free to call me on it then.