signing NPAPI plugin add-ons install via XPI

In FF 41+ all add-ons have to be signed.  I have an XPI add-on that installs a NPAPI plugin.  I set the extension type to "2" in the RDF.  When I submitted it to the automated portal for signing it said that the extension contained binary code and that I had to submit for manual review, and that I had to include the source code.  

I thought plugins did not need to be signed via this new policy, yet the loophole here is that an XPI that installs the plugin does.  

Is there any way around this?

-shoek