This recent statement by Hawking came to mind when reading the OP. For the sake of argument, assume that the message in the OP is real. Well, according to the message, those in power have already told them (the beings who sent the message) to "shove off". Now, coincidentally, Hawking makes this statement at the same time this message comes rolling around. The thought that comes to mind is that Hawking is part of the problem and is a mouthpiece of the power elite. If and when the aliens show up, people will remember Hawking's statement and be fearful and ask the gov't for protection, possibly sabotaging the "meet". Think of all the "evil attacking alien" movies that have come out over the years. Is it just a creative producer/director, or a directive from on high?
See how easy it is to concoct a conspiracy theory?
Ok, I hate to sound cruel, but here we go, so fasten your seat belts. This may even be low for me, but I will say it now the less. I think if the aliens believe that Hawkings is a mouthpiece, they will have no problem with working him over until he sees things their way.