gzt: Since nothing spiritual or specific has been raised about this incident...

From the article:

Both Taranaki iwi and the Department of Conservation are disappointed a party of trampers assembled a trampoline on the Pouakai Plateau, given the same group was told off in 2011 for having a barbecue on the summit of Mt Taranaki.In Maori culture the head of important mountains is regarded as tapu or sacred.

The Pouakai Range was a culturally sensitive site because it was a maunga (mountain) in its own right - as was the Kaitake Range, she said.

Taranaki Iwi Trust would prefer to be notified if potentially culturally insensitive activities were carried out in the park, she said.

Why was the iwi disappointed with the party assembling a trampoline? 

My take on it is because the trust would prefer to be notified so it can be discussed prior and everybody connected is happy as larry. It looks to me like this is what the trust expected from the group after the incident and apology last time. The trust appear to have been surprised when the group posted pictures of a new activity and were reacting to the lack of discussion from this group in particular rather than the activity itself. Make of it what you will, but that is my take on the excerpt above and what has been published in general.

To some extent there is a perception that the group does these activities to draw attention to itself for the benefit of its associated Christian/charitable activities. That is what came up last time. The trust may have a perception the group is more of an organised group than it may or may not be. I could not tell you either way but it looks like a factor in the blue.

Helicopter operators were mentioned earlier. These operators would have a relationship with DOC and DOC would in some way relate their activities to the trust and the operators likely know what is sensitive and respect it. The trust rightly or wrongly appears to be looking for a similar level of communication from this group on that basis.