This should be marked as an opinion piece. I struggle to find the data to back this article. Even the recruiting agency interviewed for the article gave a wishy washy answer.

It may be unfair to make a "black mark" on every journalist at The Guardian, but after the false "WhatsApp considered harmful" stories, I am unable to take anything they print at face value. Response by moxie: https://whispersystems.org/blog/there-is-no-whatsapp-backdoo...