I have noticed that pretty much all of this "what about Beirut?" concern trolling has been carried out by conservatives who avoid participating in these trends of displaying support. They are clearly using this as an opportunity to score political points against what they see as a liberal hegemony in the media.
I'm seeing it on my liberal, young adult Facebook feed by arts students and the like and on sites like HuffPo. I don't know if it's strictly conservatives who are pushing it.
That's exactly where I'm seeing it too...granted that group contains 80% of my Facebook feed. It's still going on too, still noticing people posting articles and all that, but now things are starting to shift back towards Black Lives Matter and internal social issues, as it has been for the past lot of months.