To be fair, Apple has a long tradition of naming frameworks Core Something, e.g. Core Foundation, Core Graphics etc.
I think these had their initial releases even before .NET Framework 1.0 (and so even longer before .NET Core) so Apple could probably claim "prior art" or whatever this would be called (IANAL).
I think these had their initial releases even before .NET Framework 1.0 (and so even longer before .NET Core) so Apple could probably claim "prior art" or whatever this would be called (IANAL).