I'm guessing from the description that the company is in the public eye (i.e. post-public launch), so revealing what the company does or too many details would

I'm guessing from the description that the company is in the public eye (i.e. post-public launch), so revealing what the company does or too many details would identify the company. Early stage YC companies with revenue are rare enough that someone could make an educated guess and identify them anyway, those details would confirm it. And I presume there's a reason they don't want to be identified (if for example as ffumarola suggested they've lost their tech lead; which if made public could damage product sales).