His source is Musk, who also gets money from selling the book where this quote originates. He’s also an idiot.
The fact is though that Starlink was never premitted to operate in Crimea or any territory under Russia’s control before the 2022 invasion. Occupied parts of Ukraine (excluding Crimea, which is also really an occupied territory) are something of a grey area, and it’s possible that Russians have subverted checks that SpaceX had to prevent Russia from using the technology, but Crimea was always a clear cut dead zone for the service.
They couldn’t really “turn it back on” as it was never on there to begin with. The submarines simply left the operational zone of the service, they weren’t switched off.