I should weigh-in on this discussion given I wrote the description for 'nesting birds'.
Before i start let me say that I no longer have any influence on committee deliberations other than as a general member.
Let first address Wilson's post re: Malleefowl. A male attending the mound to either prepare for egglaying or regulating the temperature of the eggs should by virtue of the current definition be considered part of the nesting process. One key factor is that the actual nest is not visible nor are the chicks and so there is a major component of the definition that has not been violated. However, if in taking the photos, the male does not regulate the nest temperature correctly because it leaves or does not come to the mound at a critical time because there is photographer 'sitting' on the mound, then this is against the ethical behaviour we strive to develop in our members.
Some years back I was in Victoria and a farmer tried to convince me that Wedge-tailed Eagles only feed their chicks every 2-3 days. Why did he come to this view? He had a 'cherry-picker' parked 3m from the nest and sat there in the open all day waiting for the parents to return because another photographer told him of another pair of birds who remained on the nest when a person climbed into the nest --- I don't think I need to make any further comment about the behaviour of some people.
Hollows are difficult to apply one interpretation. Over 75% of our Australian species either roost or nest or use hollows for both roosting and nesting. A bird at a hollow doesn't necessarily mean there is nesting occurring but feeding checks at the entrance does. In general the photographer is some distance from the hollow and rarely at the same elevation. Again the responsibility should rest with the photographer and not a long and exhaustive set of rules.
The policy we originally put in place was intended to stop photographers from 'sitting' on nests, in particular the nests of passerine species. Many of the reasons that make these species more vulnerable than non-passerines are detailed in the current ethics policy. For birds photographed away from the nest being constructed, collecting nesting material or insects to feed the young should not be an issue if the nest is not in the immediate vicinity. If on the other hand, the photographer is aware that the nest is two steps to the left of their lens then common sense should inform the 'human big-brain' that this is highly likely to impact the nesting process and one should leave the vicinity.
Again, we could write 300 pages of rules, the reality is that it should come down to the responsible and ethical behaviour of the photographer.
Lets finish by reviewing Wilson's example a second time. The scenario is a photographer walking quietly through the mallee and comes upon a male Malleefowl tending his mound. The male runs off -- does the photographer follow or sit and wait -- neither is acceptable, On the other hand, the male stays, the male goes about his business and the photographer snaps off a few shots and quickly leaves. He/she submits a photo to the website. One scenario is a photo with no comments --and as a moderator I'm left wondering if there were any ethical issues in the capture of the image. Another photo has a a description in the Comments field, which says "Finding the mound was a serendipitous encounter and as the male went about his duties unhindered I captured a few shots and quietly left the location, leaving the male continuing his duties". As a moderator i would almost certainly publish the photo. Why? The photographer has taken the time to add a description and has clearly considered the ethical considerations and displayed responsible behaviour. The fact that there is no 'nest' with eggs or chicks in the photo means that I have upheld the our ethical values.
I hope this helps; as a scientist required to adhere to and promote ethical behaviour, I take the view that if in doubt I will not take the photo, the birds come first.
Cheers