You don't need to know what the message is about when you know where it comes from and where it's going. A lot of security breaches come from that king of knowledge.
It's not that easy as just checking a box that says "enable decryption". Not saying they can't decrypt traffic, but it's not trivial if you don't have the private keys.
The NOC should have access to every single data packet sent and received through the Starlink network.
If Starlink provides the encryption then they can decrypt as well. However, as you say, the metadata is more than enough. I just wonder how much information he’s passed on to Putin.