> Disney couldn't then claim that Claude does not in fact have permission because Disney's use of the tool in such a way mean Disney now has unclean hands when bringing the claim (or atleast Anthropic would be able to use it as a defence).

Disney wouldn't be able to claim copyright infringement for that specific act, but it would have compelling evidence that Claude is cavalier about generating copyright-infringing responses. That would support further investigation and discovery into how often Claude is being 'fooled' by other users' pinky-swears.