Help. Child accused of sexual harassment

CeCelia

So my friend's son, whom is in the 5th grade, was accused of saying that he wanted to rape a girl and have anal with her the other day. He didn't. He had gotten into a fight with a friend of his who frequently talks about sex and porn and this guy started this lie about him to get back at him. The principal refused to listen to my friend's sons side of the story and kept yelling at him to tell him what he really said. He has been kicked out until Thursday and may face juvie time over this. The principal brought in more kids today that testified against Logan saying he did say it, but the original story just involved 2 people so they weren't even there and we suspect the guy that started the rumors got to them before the principal and either persuaded them to lie or threatened them. They talk to a juvie officer tomorrow. What can they do to help their case? I'm having her look up convos that her son has had with this kid to show how her son doesn't talk about sex or rape but his friend does. I'm having her bring up convos she has had with the principal whom she has had repeated issues with for several years. I'm trying to get her to find as much evidence as she can to discredit character or show bias of the situation but is there anything else she could do? This kid didn't even know what porn was until a week ago when his friend kept talking about it. He's a good kid. I want to try to help him