> In what objective way could you consider Telegram to be technically more secure than WhatsApp?

Firstly mahnouel didn't write "more secure" but better.

Secondly: if backups are enabled WhatsApp at anyone of the group members then WhatsApp is automatically uploading unencrypted copies of the group chats to Google.

I'd say that brings WhatsApp security for groups down to Telegram level at least.

Thirdly: forcing others to use WhatsApp to be part of the group gives away their group affiliation to Facebook. This might or might not be a problem for you.

Every app eventually turns evil. I'm too cynical to believe telegram or signal aren't going to cash in.

Signal has already implemented some cryptocurrency which the founder of the foundation has an unknown and undisclosed level of investment in.