That's a fake photoshop bro. Had he put that tick towards the edge (like the grey single tick), it would have been believable.
There is no way that he can read from notification and not opened it. When a user presses Mark as read button, that will send the trigger to WhatsApp that user read the message.
However, one might argue that user presses Reply so that trigger might be sent.
WRONG. Basically That launches a Reply from notification intent with a color matching the notification icon color. Here the user can type whatever he wants. Till this point, it is the interaction between the user and system, which does not involve the app yet. Only when he presses the send button does WhatsApp get the trigger.
Technically this is impossible on Android. Not sure how stuff works on iOS, but I don't think this is implementable there either unless an iOS app developer can reply to my post.
I am not surprised either that this is coming from technology "JOKE" jock.