Elfutils likes to directly access /proc/PID et.al. This only works when the running process is local. For the remote case elfutils needs to call back accessor methods supplied by the client. libunwind provides an example of this.
There is no bug here. The simple dwfl hooks that use /proc are for examples and for simple tools with the -k/-p options. There is a callback API for real applications using the libraries to use. A real application does not want elfutils doing that work for it anyway.