MAC blacklist on a per node application

I think this is somewhat antithetical to the concept of the Orbi (and mesh systems, generally). The whole idea is that devices should just connect automatically to whichever AP has a better connection. Perhaps what you need is better AP switching? Maybe periodically the router and satellite(s) should survey all the wirelessly-connected devices and attempt to optimize their connections, so, e.g., if your Chromecast is connected to a satellite, but has a better connection to the router, the system can determine that, and suggest (force?) the Chromecast to connect to the router instead? It is possible the issue is with your device, and not the Orbi, and that your device is the one insisting on remaining connected to the suboptimal AP, despite the Orbi preferring a better AP.

Take some reading of the IEEE 802.11k-2008 and IEEE 802.11r-2008 standards to understand what happens on a wireless network, between the client STA which does maintain it's own list of STA (Radio MAC, channel, signal level and quality, time), AP STA maintaining lists of neighbours, the wireless network supporting fast roaming of STA to different AP, ....

Adding MAC (BSSID) block lists on some radios would perfectly break this already very complex system - that what randomousity already explained.

Interfering at that level would be even worse than the already very bad historical Netgear enforcement (enhanced by the Smart Connect capability on newer routers) of having to define dedicated SSIDs on each radio, on each extender radio,... killing any network backed support for STA roaming - what will happen in these set-up is that a client will stick connected until the signal is almost lost. Even if better radios would be reachable, the client STA will stick to the one radio with that specific network name - because the other radios have different network names. And seriously, I can't see any reason why one want to go back to this kind of a mess.