Informative, though the idea of spattering someone with battery acid as a weapon is pretty old, since people like to use the term "battery acid" to refer to any substance that feels like it burns. I wouldn't put too much thought into the edgelords talking about that. The ones talking about using etching chemicals, on the other hand, presumably know a little more about how to acquire that substance.It's less caustic than conventional cement because it's designed to cure quicker, but it still contains calcium oxide, which means it's still quite capable of causing chemical burns. It's unlikely to cause major damage this way unless it hits a target's more sensative tissues (eyes, nose, mouth).
The thing is, quick-dry cement is only one of a few caustic chemicals rumored to be used by these clowns, with battery acid in particular being one ANTIFA's talked about at length.