Could Channa's suicide also have been blameless because his physical pain made him un-useful to the non-awakened?
I mean, from what little I understand, an arahant lives as a field of merit and to lead other people as an example. They don't live for personal enjoyment.
Seeing a bhikku writhing might have disturbed worldly people or made them think that Nibbana doesn't exist ("Look at that arahant writhe and moan! What's the point in liberation if we'll still suffer?")..
His death could have been consistent with compassion (since he didn't want to harm the faithful and possibly wouldn't be in a position to teach with his illness) and it could have been consistent with a lack of aversion (since he didn't suffer while in pain even if he appeared to from the outside).
Theoretical approaches have their place and are, I suppose, essential but a theory must be tempered with reality.