Note that is still a branch, and so something that is being tested. It does not expose the final policy that LimeWire will adopt in a final release. It does not indicate that this internal branch itself will be ever integrated. So the claims made by FrostWire on its web site are illegitimate, as such claimed unilateral filter still does not exist in LimeWire.
It seems normal to first check that the filter works effectively (in a restricted version limited for the time of tests), before adding a user-configurable option that will enable or disable that feature, that users may legitimately want in their software, to void legal harassment when using that software and when they can't easily manage the licencing terms themselves. So it's up to the software to help them...
So I don't see why this indicates that LimeWire will implement the filter unilaterally. Apparently, the branch includes changes in various parts of the code, and their intrication is not evident, and it is still under development and unstable.