* Person X is in charge of a group and has an idea for a coding project
* Person Y decides to volunteer some coding time
* Person X, with full authority to do so ends, the purely voluntary relationship
* Person Y now decides that they are a co-founder and has equal rights and starts demanding compensation for the project that doesn't exist but could potentially exist in the future. They also continue to fire off emails becoming more demanding after it's made clear that the relationship has been terminated.
Were this an open source project people would think what the contributor is doing is insane. That's clearly harassment. If I fire someone on a Friday and they show up on a Monday saying that they have a right to the company's future earnings and oh, by the way, do you want this t-shirt I made about the company, I'm going to call the police.