I think you’re confusing libzmq and php-zmq.
php-zmq is a wrapper around the libzmq library - which is updated regularly. The PHP wrapper hasn’t been released for some time that’s true, but it is still actively patched and those patches are in the Docker containers we provide.
libzmq does all the heavy lifting. php-zmq is just a wrapper to the library.
libzmq is used by some of the largest in the Cloud computing industry and so is well tested and maintained.
You are welcome to use Xibo without zmq. You’ll loose push messaging functionality and the ability to run commands in near-real time, but you can use scheduled commands instead.