Just to start, there is no clear consensus of what "Internet Governance" means and entails.
Several organizations just as ICANN, ISOC, ARIN, etc, play a specific role in the development and operations of the Internet, but by no means are "representative" of the Internet as a whole, even if you claim that organizations such as ICANN are muti stakeholders.
Each of the the "leaders" are leading each organization and the sum of the "leaders" does not make them "leaders of the Internet"
No doubt each institution is important and has to play the role it has to play, but when you get into governance matters (which again is not clearly defined what "governance" of the Internet means) some institutions could be stepping out of their mission and role. Clear example is ICANN, I don't know who authorized or delegated any sort of mandate to Fadi to get into conversations about Internet Governance with the Government of Brazil. Yes he leads ICANN, but as such, he is just and administrative/executive employee.
In your particular case as President and CEO of ARIN, clearly you "lead" that organization but it does not make you representative of the Internet or its users. I can't find anywhere in the Bylaws and Articles of Incorporation of ARIN the word "Governance."
Nobody will deny any of the alleged "leaders" to participate in any meeting, conference, event, in their individual capacities, but NONE has any representation of the whole Internet.
About NSA/Snowden/etc, mixing this matter with Internet Governance make things more complicated. It would be nice for all governments to come out clear of what kind of surveillance they do on the Internet (including the Brazilian Government). IMHO this is a complete separate discussion.
Do we really want to create a "government" for the Internet ? How do you propose to select people to be representatives for all the sectors ?
And in particular how do you propose to select an IETF representative and who/how it's going to give her/him its mandate to represent the organization on other forums ?
My 0.02
Jorge