No, it operates under the very correct assumption that paid services are MUCH LESS common to shut down.
(I shudder every f&%&^n time someone doesn't understand a generalization, and thinks that a few counter arguments disprove a statistical rule).
"""See Flickr or YouTube or PayPal or Skype or Picnik or Grand Central or Picasa or Siri or mySpace or FriendFeed or FeedBurner or even pinboard's biggest competitor Delicious for examples of the latter."""
He is not saying that "free services are never carried on by their purchasers", he is saying that free services with no monetization model are in most cases not carried on by their purchasers.
Not familiar with all of them, but Flickr, Paypal and Skype, all have ways of making money and paid accounts. And Youtube has ads too (don't know about Picassa).