Since the module has both RAM and Optane storage on it, and only the Optane storage is non-volatile, all memory writes would have to be written to the Optane storage instead of the RAM before they could be treated as complete. This would probably be significantly slower and would somewhat restrict how cleverly the device could manage the RAM/Optane resources. (For example, with the current architecture, if a memory region is being repeatedly rewritten, it can just keep it on the RAM and not touch the backing Optane storage.)

It's also unlikely that this feature would be deemed useful given that they already provide the App Direct interface; for a server (which appears to be the intended market), if you've removed power from the memory, you're probably intentionally rebooting the server and would prefer that it reboot cleanly rather than have the random contents of the previous boot in memory.