Node list from Taxonomy shows nodes from wrong sites

This module ist amazing and does a phantastic job. Just ran into an issue and couldn't find a proper way out of it, I guess that's a bug. Let me explain:

When going to http://www.example.com/taxonomy/term/123 (where 123 is the term id) then I get a list of all the nodes that have that term 123 assigned to them but also those nodes that are published on another site (where the site module defines a different context).

I thought I could use a hook_db_rewrite_sql but I can't figure out how to define that SQL. The problem is that the table site_node only includes records for nodes that are assigned to one or more sites but all those nodes that are available for all sites have no record there but should also be included in the taxonomy list.

Any idea someone?