> If Github's interpretation of copyright law holds, we can train a model on proprietary code and extract concepts without having to worry about being tainted.

> If Github's interpretation of copyright law holds, we can train a model on proprietary code and extract concepts without having to worry about being tainted. IANAL, but it can be more fine grained than that. For example, courts may very well care if you obtained a copy of the source code legally before you trained the AI on it, or whether the source code copy comes from a hack or a leak. There is a difference in a court declaring that a rental agreement's clause that no parties may be hosted by the renter is void, and someone breaking into someone elses home and hosting a party there. Proprietary source code that you can obtain legally does exist, but it's a much smaller category than proprietary code in total. In the worst case, this might render copyleft unenforceable while doing nothing to most proprietary code.