how would they even know you have a FReeper account?
It’s easy to figure out on FB if someone is on there - but how would they even know about forums w/ anonymous usernames?
“but how would they even know about forums w/ anonymous usernames?”
They could just as easily demand that you bring in all computers that you own and trace everything on it. Any attempt to erase that information would be easily detected.
I think any company demanding such information deserves a return treatment. Find all information about all executives and owners of the company and destroy thier lives by making their entire life public.