But, I think this is no different than for example Stack Overflow where questions and comments can be edited and removed if they are not on topic, or in this case, where they do not follow the Kickstarter community guidelines.
And that is exactly what happened here. Comments from the spammer/stalker are not on topic. Responses to those comments are also not on topic.
Rachel had the choice to either actively remove those comments or to participate in those off-topic discussions. She did the latter while in my (no so humble opinion) removing them was really the only appropriate choice.
Kickstarter is not a forum for drama, it is a place to raise money for your project. And that should be your one and only goal if you start a project there. This stupid spammer/stalker is taking away valuable time that she could also have put into marketing her project or participating in real discussions.
The fact that this is someone who has stalked her for the past 10 years is very sad but it is not relevant in this discussion. She is the admin of the project and she has the powers to keep it on topic.