If you have a fully static-linked library you already don't have symbol interposition. Furthermore this options still allow the thinks you need interposition f

If you have a fully static-linked library you already don't have symbol interposition. Furthermore this options still allow the thinks you need interposition for, for calls from/to external dynamic linked libraries like libc. But most important gVisor is based around intercepting system calls (over simplified), for which you don't need symbol interposition.