There is a difference between safeguarding secrets and bordering on the absurd. Just because he quits for a better opportunity does not mean he is out to divulge company secrets. The man has worked at IBM for 27 years, one would think that people would respect his devotion. Even if they do not, there are other documents that he would have signed preventing the transfer of company secrets. Also, some companies seem to think that all of your experience and ideas are "theirs" since you work for them. Some even steal ideas and patents that you have created since you are an employee. The man has a right to work wherever he chooses, just as long as he does not adversely affect his old company. ie) sharing projected plans, r&d projects, salaries, marketing strategies, etc.
The sad thing is.. If he was an entry-level or mid-level employee the company wouldn't have responded. It seems they are one of the companies that does not value the dedication he had. My 2cents.