I'd say this is fairly different to the child abuse thing (which I'd never actually heard of) or the Kony 2012 campaign. For one, it's not a matter of public opinion or allegiance - nobody's going to come out and say we should be abusing (or kidnapping and enslaving) children, but people may very well be hostile toward LGBT people, or, say, people of minority religious affiliations. I didn't change my profile picture for that 'A week' thing, but I can understand why people might - especially if they're connected to social circles in which atheism is a fairly uncommon thing and may be the object of hostility; and while that's not really true in Australia, LGBT people can still face it quite a bit, particularly in rural communities. So, yeah, doing it with the aim of influencing the supreme court decision is obviously bullshit, but doing it as a display of support for the LGBT community, perhaps not so much.