If you were talking about a big time scale, you'd have a point. But I'd say that we're talking about a pretty confined time period, especially if mentioning the 2009 Cup for the Pens in the same breath as their two most recent ones when comparing this era.
If the hockey gods came down and offered you either back to back Cup wins or three Cups in six years, would you really take the former over the latter? Sure, the argument could be made that you could win more in the near future after the repeat, but I'd go with the guarantee third. And I still opened the door for them to surpass us as well if they win a Cup in the next three postseasons, too.