This is not about person to person communication
Durov is being slightly disingenuous here.
This is about the one-to-many function in telegram which is deemed to be a form of media and according to RossComNadzor subject to their regime for media registration. According to their law they can request anyone to supply information about the controlling interests in the company and if the company fails to respond block it from operating in Russia.
The law was originally phrased for TV stations, radio, news, etc. Most countries have similar laws, they are however "behind the times" and have not expanded them to cover Internet news sources. Yet. AFAIK it is the first time a law like this has been applied to an Internet service.
So Durov refusing to answer is refusing to admit that Telegram is operating a news service, which it actually does - there are channels with hundreds of thousands of subscribers. It has nothing to do with what he is saying. His argument is entirely about the "communications" aspect of telegram, not about the "news dissemination" aspect of telegram.
Now, is the law right or wrong is a different story. As they say - the law is an ass and then we copy the Russians and implement the same law. At least as far as the Internet is concerned. Putin put in the metadata collection program in 1999. We screamed about it being undemocratic, then copied it after 9/11. And so on...