Andrew is perfectly correct and so, in a way, are you, Nigel. I would agree that it is not *normally* for ICANN to run a TLD, but .int is an unusual TLD.
I think that the current contract includes .int as one of the IANA functions. In preparing the CWG proposal we agreed that any change (or hiving off of .int) needed to follow due process and any action to change this should be
decided post transition. Few saw it as a priority and most recognised that there was little agreement for dealing with this as part of the transition.
I would note that .int is seen by many as a highly political registry: making a decision will not be easy.
And I don't see your poacher-gamekeeper argument. Given ICANN has been managing the domain against a policy defined elsewhere (an RFC) for many years, are there examples of their management of the TLD that have affected their decisions
on other of the IANA functions or vice-versa?