In gtk, we do a check like this:

static void
check_mixed_deps (void)
{
  GModule *module;
  gpointer func;

  module = g_module_open (NULL, 0);

  if (g_module_symbol (module, "gtk_progress_get_type", &func))
    {
      g_error ("GTK+ 2.x symbols detected. Using GTK+ 2.x and GTK+ 3 in the same process is not supported");
    }

  g_module_close (module);
}

It would be good to do a similar check in nautilus_module_load to reject modules which link against gtk2.