So, after separating from company, you can release all proprietary information and you'd have limited liability? I thought there would be larger recourse. Not familiar with law though.

>His NDA has expired.

I've never heard of an NDA that says "after 3 years you can start giving away trade secrets"

i'm sure "we use fifty different kinds of virtualization and a hundred different operating systems" is valuable information

If you release corporate secrets you can be successfully sued, regardless.

If he is revealing gross misconduct it could be consider whistle blowing.