Tor wants to move to Rust, and they aren't happy with their C codebase. They want to expand use of multi-threading, and C has been too fragile for that.
Makes sense. But maybe the fact that that post is 4 years old serves to bolster the argument for Fil-C's value proposition. However much people may want to move away from their C code bases, the resources it takes to do so in a timely manner are often not so readily available.