I think the difference is that you've stated explicitly that you'd rather be King than Rich, while Maciej's response when asked that was "I feel like after seven years, I have a pretty good sense of what bookmarking/archiving needs people have, but am at the limits of what I can personally build. If the votes swing my way, I'd be happy to have a good-faith conversation with you", i.e. as long as YC didn't try to turn Pinboard into something it isn't, he'd be willing to listen to ideas that may help it reach more people. The difference is pretty subtle, but it basically amounts to "Is YC wasting its time with its advice?" It also helps that it's Kevin Hale opening the conversation, and Wufoo was not unlike Pinboard (or Tarsnap, for that matter).
Nothing wrong with being King, BTW, but YC's made it clear that it's not willing to play court jester.
Tarsnap is definitely not suited for YC Core. I applied for YC Fellowship -- and only YC Fellowship -- because I wasn't sure if Tarsnap was suitable or not: I don't know what YC is trying to do with YC Fellowship. (For that matter, it's far from clear that YC knows what YC is trying to do with YC Fellowship.)
Nothing wrong with being King, BTW, but YC's made it clear that it's not willing to play court jester.