The Robot Operating System (ROS) is a widely adopted collection of software libraries and tools for designing and implementing robot control software. Its rapid growth has been driven by an active community that maintains an extensive ecosystem of reusable components, increasingly positioning ROS as a unifying framework bridging academic research and industrial applications. ROS 2 importantly enables decentralized, peer-to-peer communication, making it well suited for scalable and reliable multi-robot systems. Simulations play a critical role in the design and implementation of robotic systems prior to their real-world deployment. For large-scale robotic systems, simulation scalability, that is, the efficient simulation of many robots, is essential. However, existing ROS-based simulators are unable to scale to large numbers of robots, while highly scalable simulators lack integration with the ROS ecosystem. We introduce the ROS-2-ARGoS Bridge, a framework for simulating large-scale robotic systems running software based on ROS 2. We showcase its scalability through experiments with up to 1280 simulated robots that locally interact and coordinate their actions. As industries increasingly seek to scale up their robotic infrastructures, our open-source framework offers a timely and practical solution for simulating and designing large-scale multi-robot and swarm systems.