> pretty weird/low class move to build a free clone of the product you just worked on
It's extremely common to do that. Where do you think all this industrial open source software comes from? People work on a product, then they leave the company and want access to a similar tool. Happens all the time.
If you're an expert in X, you're gonna be building several Xs in your career. That's how the economy works. An employer suing you for building another X is ridiculous. If you're not funded for legal defense, your best way forward is going public. He did everything right.
