If you are worried about being dragged to a "black site" Telegram is giving you a false sense of security. The corporation (and the owners i assume) are long gone from Russia, ironically because it could not operate there and was in danger of being censored or appropriated by the Kremlin (they never do things like that...).

Telegram sits firmly within the western legal system and somehow manages to stay online. Their privacy policy references the British Virgin Islands.