Unfortunately, we don't see any solution to this problem. Here's our personal opinion on this topic: if a site deliberately blocks certain spiders, this is very delicate. The Google Spiders also see this information. It is only a matter of time until Google discovers such networks, de-indexes and punishes all linked websites. Therefore we highly recommend to focus on sustainable backlink strategies. You can also watch our webinar replay on building backlinks: http://swissmademarketing.com/your-seo-plan-for-2014/