I think I interpreted Wheaton's post in a different way than you did. To me, the author didn't seem to make any bold claims about effects this would have, and he also did not give me the impression that he was an authority on the subject.
To the contrary, I thought the theme of his post was specifically that he didn't know how Instagram's new policies would effect personal privacy, and that lack of understanding concerns him. When pondering the implications, he even goes as far as to ask whether a worrisome, fictional scenario was even a possibility rather than insisting that it would happen.
Where do you think he expressed a sense of entitlement? He's not a user of Instagram, so I didn't get the impression that he thought Instagram owed him something.
I think his whole post is a lead in to an excellent point: in the "social web" in which we all interact daily, we are seeing more and more that you don't have to use a service in any way in order to be affected by the decisions that services make about its own users' privacy. All entitlements aside, it is becoming increasingly difficult to maintain control over your own privacy when the details of your life are extracted not as a result of your own deliberate decisions but by the decisions of others.
Opinions about whether Wil Wheaton is a self entitled geek aside, I hope we can all agree that that is a point worthy of consideration.