It's not particularly interesting. YC relies on people who leave their employers to found startups. Companies tend not to like employees leaving to start their own companies and often sue them over it, which is 99% of the time meritless and nothing more than bullying. It is in YC's interest to use its resources to prevent this bullying because it both sends the signal to other companies that they would be unwise to try to bully a YC startup and to potential founders that if they join YC they will be protected.