I have two immediate thoughts. Forming a company and then taking time off of work to raise a child for 4 month is indicative of non-ideal planning, more than anything. That said, in this case the gentleman in question is an employee of an established company, not the cofounder to a startup.

Additionally, leaving work at 5pm every day sounds great and, I suspect, may actually result in a more productive work week with happier employees. All parties win in such instances.