Casinos (real ones, anyway, not talking about illegal secret game rooms) don't really beat people up anymore.

That said, this also won't be a problem for casinos. They have very advanced anti-cheating systems these days.

The corporate casino security teams will know about this before it becomes widely available and will institute policies to lifetime ban anyone they detect using this tech, which they will fairly easily be able to do because of how much automated surveillance there is in any real casino.

In any case, there are way more subtle signaling mechanisms people can use (but probably also get caught using) to collaborate that don't involve someone suspiciously silent talking right in front of a dealer.