[stackcollision]

When he says that the employer is sponsoring learning in that company's particular area, he is right. Learning is not just sitting down with a textbook and taking notes. In most jobs, especially computer science, you're learning every day. You're adapting new solutions to problems, and taking that experience with you. That knowledge can then be applied to future problems.

His company is paying him to solve problems in a particular space. Once he solves them, he knows how to solve them in the future. When working on an OSS project in the same space, he can apply the techniques he learned at his job to that project.