The original Unix philosophy (McIlroy, Ritchie, Thompson) says nothing about source code licensing. It’s about programs that do one thing well and work together through universal interfaces.
Open source is a distribution and licensing model; conflating it with software openness misrepresents those core tenets. Orion supports Chrome extensions, Firefox extensions, and standard web APIs — that’s interoperability in practice.
That being said, the future is not written ;)