The problem in this case is not that private data might have been used. The problem is that the outcome of this research will be the US military developing a weapon that can be used to create or stop or influence political movements across the world (including inside the US). The question is whether it is a good idea to create such a weapon. War is inevitable but ever since time immemorial people have respected certain rules of engagement. Its difficult to draw the line in the sand to decide what type of propaganda is unacceptable, but it should be obvious that propaganda created using every dark pattern in the book, trained on 350B social media posts is probably not going to bode well for Earth's future. Its a lose-lose situation.