The close reason I chose is:
Questions should demonstrate reasonable business information technology management practices. Questions that relate to unsupported hardware or software platforms or unmaintained environments may not be suitable for Server Fault
Taking advantage of a "tech support mode" on a NAS box to install third-party software in an un-supported fashion does not classify as a reasonable business information technology practice.
In case you missed it, here's what Code42 has to say:
Although running the CrashPlan service on a headless computer is an unsupported feature, this article describes a process that some users have found useful.
...and what Netgear has to say about usage of Tech Support mode:
Use the tech support boot mode only when instructed to do so by a NETGEAR Technical Support representative.
While I understand that you are indeed doing this as part of supporting your company, hacking things together like this is not on-topic. We strive to build well-designed, well-supported, reliable systems.