“We have no problem with Colin Trevorrow, but he’s not the right guy to direct Star Wars Episode IX . George Lucas as director of Episode IX would be the perfect way to end this new trilogy and make an epic farewell between the Father of Star Wars and the whole universe of the galaxy far, far away.”
Not sure that 5000 signatories will sway Disney from its current course, but it’s worth a try if it’s what you really, really want to happen.
I will go on record that if Lucas directs Episode IX I will have no interest in seeing it. The prequels have proved that he is terrible at doing anything in the universe he created. Jar-jar Binks and the host of racist "aliens" should be enough to keep him from touching anything Star Wars. I am a pretty big fan again after seeing Force Awakens so I would hate for Lucas to ruin that.