Lets not forget that Mr Sandilands is also a journalist so the story has to have an element of shock horror panic built into it. I'm sure Mr Sandilands is fully aware of the function and purpose of TCAS so another aircraft would have been notified of the stealth Virgin if a collision was imminent.
doing something like 850 kilometres an hour, through airspace which includes A380s and 777s
Why mention specifically 380 and 777 if you didn't want to spice up the story?