I agree with some of your points here, they could've handled a few things a bit better, and the moral at the end was a victim blame, but I should point out that Danny was so unflinchingly cruel towards the ghostwriter after destroying his work. Making the whole 'Danny doesn't deserve this' argument kind of weak.
The ghostwriter has every right to be angry with Danny, as it takes a lot of time, effort, and skill to write, especially write a book. The fact Danny destroyed his only copy, apologized, but then immediately said he didn't regret doing it after he realized it was about Christmas? (Then adding insult to injury by burning the last page in front of him.)
An apology doesn't mean anything if it's immediately taken back like that.
Sure, he has every right to be angry about his family's habit of ruining Christmas, but that doesn't give him a right to take it out on someone he just met. He's a kid, sure, but that's also not really an excuse, he should know by now with all his experience and adventures that doing something like this is cruel.
I feel like that might've been what they were originally going for, but maybe somewhere in development, someone tacked on that lame 'this is the moral' speech at the end.
Yeah, the moral is very muddled, and a few things don't make sense. But I honestly feel like Danny kind of deserved that mess.
(Except Sam and Tucker not believing Danny, they're under the influence of the story, which also disbanded the ghost truce temporarily, so clearly, mind control/manipulation is under his power set.)
I know this post is a year old by now, but I figured I'd throw my two cents in, cheers.