@snood,
It's not "purported". The group chanting about bacon and such self-identified as BLM. It's a very big stretch to suggest that are hundreds of thousands "if not millions" of people who identify themselves as members or even supporters of BLM.
It is gratifying to learn you find the rhetoric in question to be vile etc, but I don't understand why you feel compelled to excuse it's origins.
There are indeed, hundreds of thousands, if not millions, of people who are concerned with the reality of what black Americans face.
I very much doubt that the same number of people feel insulted by the statement "All lives matter." or buy into the vile rhetoric.
There are a great many valid causes in the world in addition to the one that involves black Americans. This isn't to minimize the latter, but it is to suggest that every group that professes to further any of these causes isn't virtuous in their tactics because their cause is.
You won't lose any of your bonafides by calling out groups that are going about the cause the wrong and even vile way.