From the mainstream media article:
The key change in the terms of service appeared to be a new block from Unity on using its engine for cloud gaming services that do not have specific authorisation. Narula speculated that the change, and subsequent block was “probably either an accident or a negotiating tactic” on the part of Unity. “We’re waiting for someone in the west coast to wake up and make some ransom demands, basically.”
Obvious interpretation: They realize the value that can be delivered through using Unity as a server in this way, and want to update their existing licence agreements to extract more value (fair). But instead of being upfront about it, they're deciding to be assholes to set up a stronger negotiating position (dickish).
Worse interpretation: They realize the value that can be delivered through using Unity as a server in this way, and they're planning to develop their own Unity-as-a-server platform in place of SpatialOS, so they're blocking any possible competitors from using their own technology before announcing their own product.
Or it could be something else entirely. What do I know?
Fingers crossed guys! Hope this gets resolved with an updated licensing agreement sometime soon.