This does raise some general concerns:
i) Will Nakivo have to go through this approval process every time there is an update to the software? Unless Synology streamlines its approval process, at the current rate this would mean that the Synology version is about three months behind the released version. This may not be an issue with feature release upgrade (others may have different views) but could be problematic with bug fix or security updates; particularly given that vCenter updates quit typically break things requiring an updated Nakivo.
ii) When I've had to approach Nakivo support, I've found them extremely responsive. Part of the trouble-shooting process often involves installing pre-release, beta or bespoke builds of the software. I can't see how this would work if there isn't a means for Synology to use external installers.
I hope these issues can be resolved soon - to be honest, this is questioning my decision to go with Synology rather than Nakivo. When I need to update\replace my NAS, I'll certainly be looking at what other options there are.