The article centers around activity in Syria, but the problem is much more endemic. In the United States, Apple has consistently taken down apps providing information about US government airstrikes - including those that strike wedding processions, children, bystanders, etc. Recent efforts to identify and scrub foreign propagandists in the United States have silenced legitimate voices of domestic dissent, as foreign influence campaigns typically attempt to magnify grassroots dissenting opinions (this is true also of US foreign intelligence efforts). There's many reasons why these kinds of apps, comments, and conversations are taken down due to their content.
Fundamentally, being a gateway to information in a legal environment where the hosting the content as a curator puts you under risk creates deep incentives to whitewash content. Those forces are already present for companies which might accidentally sustain 9gag/4chan type cultures/commentary which contradicts however its productizing its platform.
Reddit is another example a company that has recently scrubbed itself of most controversial content, including content critical of or dangerous to its host's countries political and national security naratives. Twitter has started down that journey as well.
It feels like we're experiencing the growing pains of social network and hosted content boom reinvented on web technology over the past couple decades.
It's kind of amazing in retrospect how controversial some of the "mundane" applications of technology to society have been, whereas a couple decades ago most of the moral panic centered around concepts like "online dating", which to date have actually been relatively controversy scarce.