The private module itself is now a public module, if you want to let the others use it. I get that you really value your work to the point that you don’t really want to share it. Anyway, you can say that the main reason the private module has to be set to public for usage by other developers is to allow them to see your code.
I do think that Roblox wants their developers to get the most access when building their game, whether it’s for safety, security, or other reasons.
Until now, I’m not aware of any methods that would allow you to hide your codes from others while you let them use it. If such methods exist, then there would be a high chance that Roblox would patch it up again, perhaps for the same reason.
To not worry about it, you say? Roblox respects Intellectual Property (IP), which is a major part of a huge corporation. There’s a post that you might wanna read related to it, [Private modules] New way of securing code? - #15 by IdiomicLanguage Good luck!