It's how they see it, apparently. Same with all the "OK" hand gestures. It's a dog whistle intended to empower those that agree with this crap to start doing it publicly. "If Elon can do it, so can I"...etc.
Sure, but not everyone carries around a cross for just such an occasion. Everyone's got their fists on them, though (well, unless you're an amputee -- in that case, bite Nazis.)