Dracho is definitely right. If you treated the man properly and let him know that you were not the one responsible for his firing thenyou have nothing to feel guilty for.
You can still write him an excellent letter of reference to help him get a future job.
I have never been in either position here but have been called in by my boss for an undeserved reprimand. He started by explaining the situation. It seems that his bosses decided that the one day I had not accomplished half as much as they expected and wanted me reprimanded for it. I had in fact accomplished
more than my direct boss had believed possible and he had previously done my job before being promoted. I left that company as soon as I had the chance. I don't hold anything against my direct boss. He even gave me a superb letter of reference, which I have never had to use. They eventually gave up trying to find someone who could fully replace me. The person I believe responsible was eventually promoted and directly caused by his behaviour the unionizing of the business. I would believe that the union made his life hell as he was the type to provoke them constantly with BS.
Whatever you do don't break the law. It may be satisfying for the moment but it is not worth wrecking your life over.
Someone like the person responisble will always have their own issues that can be made to haunt them. I've seen that with others. I can think of several people that have lost their jobs because they were that sort of person and provoked too many below them. Including one that provoked me directly
. One of them later applied for a job with a company where a former co-worker was employed. The former co-worker was asked his opinion and it was "if you hire him I quit", he didn't get the job. If he had been a different person it would have been "hire him now".