Right, I concur with the reasoning that contributory infringement could be argued against the developers, but I think the interesting questions is whether that reasoning can be extended to the "material" under the takedown section - particularly as written. If so that seems like the kinds of thing that could get ugly very quickly. E.g. are instructions on how to google for infringing material suddenly infringing?
I understood that DMCA notice/counternotice procedure was meant to provide a streamlined process for simple cases, which could be migrated to an actual court if necessary. I don’t like seeing it stretched to cover cases that aren’t so simple.