Comment by Canada

This doesn't make any sense. Either the author of the article is confused, lying, or is drawing conclusions from source material that is untrue.

In the US case, there was a phone where data was encrypted at rest. Though Apple was capable of creating and signing a firmware update that would have made it easier for the FBI to brute force the password, Apple refused to do so.

In the Russian case, the FSB must have already had access to the suspect's phone because if it did not then Telegram would not be in any position to help at all.

So, the FSB must have already had access. And therefore, by having access to the phone they also had complete access to the suspect's chats in plaintext, regardless of whether or not the suspect used Telegram's private chat. There would have been no keys to ask Telegram for copies of.

Alternatively, the FSB might have had access to some other user's chats with the suspect, and wanted Telegram to turn over the suspect's full data. Telegram is 100% able to do that if they want to.

As the specific part of the article you have quoted is definitely bullshit, I suspect the rest of it is bullshit too and that despite what Roskomnadzor states in public, the real fight with Durov was over censorship.