I would agree that if the course faculty provide significant and non-trival starter code, then publishing the solution would be a copyright violation.
Some DMCA claims do indeed mention "The repository [from the student] contains code provided to complete assignments [georgia tech]" ([1]). But the claim at [2] does not mention this. It only says "This repository contains Georgia Tech class assignment solutions." under the section "Please provide a detailed description of the original copyrighted work".
If the solutions have been copied from a set of solutions published by the university, they will have copyright. If the solutions are the students own work, then they won't, and this is abuse of the DMCA.
For the sake of a mind game assume that assignments and solutions can be copyrighted.
The mind game is: The assignment is most likely produced with a solution, but published without (lets say else it would not be 'assignable'). For deterministic solutions, could you copyright it without publication?