The reference source license doesn't allow any use but reference. Does that help Mono? Wouldn't the possible pollution still mean someone that's seen the source can't contribute to Mono? (I had the private shared source access in 2004; AFAIK Mono would still ban me from contributing.)
"This means that folks like the Mono team could look at this Reference Source and not have to gouge their eyes out afterwards. "
Very reassuring as well.