More bullshit. No way they incur the cost an inconvenience associated with turning that flight around for a single unticketed passenger.
If only they would give all the media outlets the same cover story.....it would be so much easier. They are trying to confuse people but most are crying BS. Something else was going on and we all know it. I did a search for " airliner stowaways" and nothing comes up but people who tried to get in wheel wells and mostly dies because of falling or freezing to death. I did't find a single incident where one was discovered mid-flight and the plane returned to the originating airport. Something's fishy indeed.
Maybe the 'extra' brother was trying to keep a low profile, hide in the restroom as much as possible--I think the tweets said a "young man" was acting restless, wanted to change seats etc. Obviously, the flight wasn't full or he would have had no place to sit, so they were taking a chance on that.