Interesting post on Phill's blog about hetero-phobia: http://virtuphill.blogspot.com/2010/10/anti-hetero-rhetoric-implicit-or.html

Here my thoughts:
There is a slight difference between saying: annoying black couple and annoying white couple. also between straight couple, ick and gay couple, ick.

All depends on the society this happens in.

Power structures in our society favour people who have certain characteristics. The word power always sounds very strong. Actually it's just about being considered to be "normal".

So a normal person is a man. A normal person is white. Normal history is European history. A normal person is heterosexual. At least in our society here.

So when you put a sign on a toilet the men's gets little man, the lady's gets the skirt version of a man. Things are real/honest/traditional or ethnic/"World"/International. You can watch a romantic movie/romcom or a gay/alternative film.

In this country you can also speak normal or speak funny.

All that excludes quite a lot of people (both the non-normals and those who don't like to see the non-normals excluded). And these people either shut up or say things that shock the ones belonging to the powerful groups.

I don't know your facebook friend but she/he may have meant to raise awareness for the hetero-centric worldview and shock people by saying that couples are not automatically heterosexual. It could also have been just a discriminating statement, which would be wrong. But not as wrong as "ew, a gay couple" as the gay couple is not in the position of power, doesn't receive protection and confirmation from society and cannot just brush off these hurtful comments.

But yeah, in the status, the word was unnecessary and wrong.