While Physical Internet (PI or \(\pi \) ) systems have shown significant promise for improving environmental and economic performance in logistics, the integration of social sustainability objectives into PI-based decision models remains underexplored. This paper addresses this critical gap by embedding driver rest periods as a social Key Performance Indicator (KPI) directly into the operational logic of a holonic simulation model for a multimodal PI hub. The model explicitly couples container recomposition decisions with truck availability, ensuring that outbound containers can only be dispatched when trucks have satisfied mandatory rest constraints. This dynamic interaction introduces a systemic trade-off between efficiency and equity, allowing the evaluation of how human-centered policies influence key performance metrics such as throughput, waiting times, and congestion levels. Simulation results demonstrate that the model can accommodate social constraints without generating systemic bottlenecks, while revealing an emergent synchronization between container flow and truck dispatching. This work contributes a novel methodological framework for balancing efficiency and social equity in the design of PI-enabled logistics systems, offering practical insights for researchers and practitioners seeking to operationalize human-centered KPIs in future supply chains.