Talking about whether it is a good approach or not, I would say yes! RabbitMQ is a great approach and makes it very easy to communicate between systems, through the internet. As long as each machine / process can access the same RabbitMQ (server / cluster), you should be ok.
But the crucial question is if rabbitmq secure enough to do that?
As long as you follow standard security practices like any application on the internet, it should be fine.
Just make sure you use firewalls, use SSL, set secure usernames and passwords with limited permissions, etc.