[BIP Proposal] Mempool Validation and Relay Policies via User-Defined Scripts

He acknowledges the potential of a txnotify-based approach but highlights its limitations in comparison to his proposal. McClelland points out that relying on a single external binary for running policy validation logic undermines the modularity and sandboxing benefits offered by a more distributed arrangement of scripts. This setup, he argues, would be less flexible and might not support the easy customization and scalability that modular scripts do.

Furthermore, McClelland raises concerns regarding the security implications of fetching relay policies over the internet. He suggests that such an approach could introduce vulnerabilities, as it would depend heavily on external data sources. In his view, policy updates should ideally necessitate direct user intervention, reinforcing the system's integrity by reducing dependence on potentially insecure internet-based policy retrievals. This perspective underscores the importance of maintaining a secure and user-controlled environment in the development of Bitcoin-related technologies.