In a capitalistic society, don't expect a company to have the best interests of its former employees in mind. Expect a company to have the company's best interests in mind. Expect the company to be most concerned with the bottom line.
In a litigious society, don't expect a company to sit back and let a former employee sell unlicensed material, material developed while the employee worked for that company. Expect that company to sue to protect its property. Expect that company to ask for monetary restitution.
Is such a lawsuit always morally right? Perhaps not. Is it legally right? Probably so, assuming the contract/employment agreement states as such, and assuming the company's lawyers are well versed in what legal rights the company possesses.
In a nation where companies routinely rape the land, poison the waters, destroy the forests, pollute the oceans, and produce products in overseas sweatshops, don't be surprised when a company tramples the little guy for doing something the company perceives as being wrong. Actually, trampling on the little guy is a relatively minor evil compared to the greater evils of corporate America.