This is true, but not currently relevant. The cost (difficulty) of training does not indicate how good a fit the model is for copyright protection.
I suspect that part of the arguing this out in court will be making those economic arguments as part of an attempt to extend copyright protection to model weights - but that is a separate issue from if they are protected currently.
Part of the economic argument for copyright is to encourage the investment of time into producing new works, so it may be a persuasive argument for extending protection. Although (relatively) recent history suggests that persuasive argument is not as powerful as giant wads of cold hard cash in extending copyright coverage.
I suspect that part of the arguing this out in court will be making those economic arguments as part of an attempt to extend copyright protection to model weights - but that is a separate issue from if they are protected currently.
Part of the economic argument for copyright is to encourage the investment of time into producing new works, so it may be a persuasive argument for extending protection. Although (relatively) recent history suggests that persuasive argument is not as powerful as giant wads of cold hard cash in extending copyright coverage.