I don't think you read the article. You don't need to do anything extra for Spartan.
Can you explain what circumstances require that you support IE7?
If he's a developer for a company that still has apps that require IE7, then he needs to support IE7. It doesn't need to be on the public Internet at all.
I work for a company that has a "managing" application that runs on windows. This application has a browser plugin that runs in an equivalent IE7 environment which must be supported.
Unfortunately that is what you get with proprietary sometimes.
I always hear about these applications but I've never actually seen one.
Your case is isolated, IE7 is pretty much dead.
IE7 has had very little usage outside of enterprise for a few years now. If you're screwed by your job, sorry. Maybe all those well-paid people can come up with an upgrade plan.