No, Leah Remini is not a traitor to Scientology. She is an individual who had a bad experience with an organization and feels a need to tell others about her experience in order to help them avoid a similar situation. In addition, she is a high profile person which gives her an added responsibility to inform others.
I came away with the feeling that the church of Scientology is not very professional, but rather petty, vindictive, and mean-spirited in their retaliation against members who chose to leave. Before I viewed their own sites, I was open-minded, a clean slate, willing to hear their side, but afterwards, I felt they were a childish group run by incompetent people, and wanted nothing more to do with them. Kudos to Leah, thank you for speaking out.
Leah Remini made the decision to leave Scientology when she was thirteen. This was when she was a rebellious teenager, going against her upbringing but also when she was discovering the world and her own place in it. Leaving a religion, whilst still a teenager, and before an adult understanding of committing to a religion has been gained, is not wrong.
Leah Remini is not a traitor to Scientology. She came to realize that the so-called religion was detrimental to her and to her family. I'm sure the church doesn't like her comments, but she also has some positive memories of Scientology and its focus on being your own force for good etc. She was raised as a Scientologist and as an adult realized it wasn't the healthiest thing for her family.