Zuck is on a major PR campaign drive, I would not trust a word he says.
He also said that he doesn't visit Russia anymore, yet a recent FSB leak indicates that he was frequenting there. And before that he heavily marketed Telegram as ad-free forever. And before that there were quite weird populist PR tactics when professional cryptographers pointed out Telegram's crypto is a mess.
YMMV, but I wouldn't trust a single word from this guy.
They can earn a lot of money via Telegram Bug Bounty Program if they can prove it