Where are you seeing that Solitaire was bundled in Windows 2.1? Both the wiki page you reference and the Wes Cherry's linked comment both suggest that it was originally included in 3.0.
EDIT: re-reading I see that he later on says it was eventually bundled in 3.0. So he wrote it for 2.1 and it didn't get picked up until 3.0. In either case, source referencing 3.1 in a comment is clearly not the original intern-developed source from 1988, although it's likely pretty close.
What if Wes, the intern, wrote Solitaire for Win2.1, then it got redone for Win3.1 et al. by someone else? That makes all of this somewhat morally underhanded.
I thought I'd ask here. https://www.reddit.com/comments/3zfadv//cyntkus
Of course, I'm incredibly late, so it might never be seen, but who knows.