Quaoar, That is exactly what they will do!
First off, If I remember correctly there was a story about $cientologists selling SeaVegg as part of a scam not to long ago.
Narconon is a major recruitment tool for the cult. Some are not directly recruited into the cult but are recruited into one of their many front groups.
If you can you need to get your friend to review the information here on www.xenu.net
to start with. The only way to avoid a trap is to know of it's existance. By planting the seeds of doubt now, before the cult can fully destroy the critical thinking skills of your friend is his best hope of avoiding falling under their spell.
If I can be of any assistance please PM me.