I think if you define "signaling" as "wanting someone to know about it" then of course any social media communication is "signaling," but then is any communication at all. Oviously when I speak I want to be head, so it's not "I don't care if nobody knows about it."

But I think that's far too broad a definition of "signaling." The original article says "Building social capital through signaling."

When you post about your gardening to see if there are any other gardeners you can connect with, I don't think it's necessarily to "build your social capital," yet you can prove that it isn't.