The biggest issue of fuchsia isn't its license, it's rather the design choice to allow proprietary driver blobs. Linux, for the exception of a few blobs here and there, rejects such an idea. In other words, the question is less about license and more about attitude / tolerance for proprietary extensions/tooling. The main power that an open source maintainer has is the design of the codebase and what to accept inside, not the power to litigate a copyleft license. The more it cooperates with proprietary software, the more likely proprietary software can establish itself and restrict user freedoms.