In what context? You are planning on commercializing Copilot and in that case the calculus on whether or not using copyright protected material for your own benefit changes drastically.
It isn't. US copyright law says brief excerpts of copyright material may, under certain circumstances, be quoted verbatim
----> for purposes such as criticism, news reporting, teaching, and research <----, without the need for permission from or payment to the copyright holder.
Copilot is not criticizing, reporting, teaching, or researching anything. So claiming fair use is the result of total ignorance or disregard.
In what context? You are planning on commercializing Copilot and in that case the calculus on whether or not using copyright protected material for your own benefit changes drastically.