Clearly, they are sympathetic to Black Lives Matter, and don't particularly hide it, it's right there on the page! "Front" to me implies that a) they are operated by the thing, not just sympathetic, and b) they try to hide that fact.
Those things don't appear to be true? But sure, you can tell people they are sympathetic to Black Lives Matter movement, if you think this is important context for their facebook reporting re-posts, why not. About half of the USA would currently apparently agree, and half disagree, with that sympathy. (I don't think the half that would agree are all 'fronts'!)
I don't know if they are sympathetic to "antifa" or not (which is not the same thing or people as Black Lives Matter, despite right-wing talking points), but... I am, personally.