Shutting down the product is exactly what they were trying to avoid. As a business owner, he made commitments to his customers to support the software he sold them. Walking away from those commitments would have compromised his reputation and hurt his ability to sell in other new markets. I think it was primarily a personal obligation he felt towards his clients, and a matter of integrity.

In the B2B space, the costs of switching vendors/products is often a really big deal. Spinning the product off released him from the obligation (allowing him to focus on more promising products), and avoided (most of?) the pain for his clients.