There is nothing unethical about 'call me if you have news'.

However, having pre-written copy introduces vast amounts of bias by shifting how people are thinking about an issue. Thus, you can't rewrite it without first being influenced to think along similar lines. Now, one option is a simple firewall that prevents the person writing the story from reading original copy. More effort in the short term, but companies would have less incentive to try and shape the news for free press.