I am not at my computer at 3AM, so I cannot easily start a Wireshark trace to see what is being sent to MS via the new task that runs then. And I assume that the packets would be encrypted, so a trace would be useless, except to get the IP address of the
destination IP server.
If you wanted to get more information on the MS Compatibility Appraiser task (without having to get up at 3am), you could change the time of day (in Scheduler) when the task runs.
Not only do I never intend to upgrade my current computers to Windows 10 (or 8.1), but I have lost trust in Microsoft ... so I have hidden all windows "nagware" patches/upgrades (such as KB2952664, KB2990214, KB3035503).
If Microsoft wants its customers to install Windows 10, then rather than using "nagware" to trick/nag people into installing it, they should create an Operating System that is so good, and so compelling, that people will be lined up waiting to install it.
Unfortunately, it appears that Microsoft has forgotten how to create such an Operating System.