The key is if a person can put aside the views, be impartial and only really on the evidence, facts and arguments presented in the trial. Very much doubt a Trump supporter could do that, given how closed minded they are
The Judge, prosecution and defence all get to participate in jury selection, they are also quite experienced in doing so even it these modern times with social media and 24 hour news cycle. The fact that it's only taken them a day to seat 7 jurors demonstrates that, some were suggesting it could take two weeks to select a jury but looks like it will take much less time
