I think you summed it up perfectly. If your boss is no longer paying you, he has no right to your time. Just like with the pirated content, if you don't pay for it, you have no right to it.
Merriam-Webster:
"Definition of IMMORAL
: not moral; broadly : conflicting with generally or traditionally held moral principles"
Based on this, whether piracy is moral or not depends on people's opinions. I would argue that society does not consider copyright infringement to be especially immoral.
Sing 'Happy Birthday' in public without paying the guy who bought the company holding the copyright to it. Is your audience disgusted by this immoral act?
Now the owner of the company holding the copyright sues you for your unauthorized use of 'his' song. Would more people think that you acted immorally, or that the copyright holder is acting immorally?
But with the pirated content, the pirate never entered into an agreement to pay for the content.
Also, the creator of the pirated product has only lost a potential sale (one that I would argue that they don't have a right to anyway), whereas the unpaid worker has experienced a 'theft' of their time and work.
