Snowden doubts security of Telegram
rt.com
rt.com
Pavel Durov repeatedly denied police and FSB access to user's data while running VK (basically, Russian Facebook).
Finally, his company was stolen from him by shady businessmen with government connections.
Just keep these three facts in mind while reading this article.
Snowden is right in talking about MTProto's issues, and this is a case where he can talk about something both he and the Russian government dislike, albeit for different reasons. It's a fine line to walk to maintain integrity.