This is the second tweet I’m seeing phrased like this. It lacks context and is provocative, perhaps deliberately? It seems to encourage detention centres to find a cheaper way to house asylum seekers instead of saying this is bad no matter what the costs involved are. The article itself is better. On particularly hot and/or controversial topics, such as immigration, many people often tweet or post links to articles on the topic to be seen to be engaging with it instead of actually engaging with it (such as by reading it and then sharing their original comments).
Some publications like to take advantage of this because such behaviour promotes the article’s circulation, potentially exposing it to more readers and making it a part of social media conversations, or flame wars. It’s all neither right nor wrong but I think it’s unethical: feeding poorly qualified arguments to a mob is like fanning the flames, then basking in their warmth. Even if Vox isn’t deliberately doing that here, it’s careless to assume its tweet will be interpreted one way when it hasn’t provided the necessary context for that to happen.