This article, like many others, seems to overestimate how large the actual numbers of developers is at Microsoft, as opposed to full teams with Test and mgmt and their associated marketing, sales, etc. organizations. The .NET GC was roughly 1 person (sometimes a little less, sometimes a little more). Most of the base class libraries were one person. Even larger things, like the text editor, were usually a senior pers…
Not to be obtuse, or maybe miss the joke, but how can you sometimes have a little less than 1 person working on one of the most important parts of your runtime? Sounds like a bug more than a feature to me. :)
You make sure that person knows a lot about garbage collectors? If he's implemented garbage collectors before and is up-to-date on GC research, there's no reason one person couldn't implement it alone.