Whatsapp is considered insecure and banned from use for military in Russia. Telegram, on the other hand, is widely used. Of course that's not something definitive, but just a food for thought.
...that telegram is backdoored by the russians? The implication you're trying to make seems to be that russians must be choosing telegram because it's secure, but are ignoring the possibility that they're choosing telegram because they have access to it. After all, you think they want the possibility of their military scheming against them?
Perhaps you're simply struggling with the concepts here: would it help you to understand things better to add that russia and the US ban the use of Signal by their militaries and intelligence services?
Did you detect an implication that can't be extrapolated from the text without metacontext and secondary unstated axioms, or is your mind totally blank and baffled at what these data points could indicate?