Silence through contracts

A reader writes in:

Essentially the developer sold off most of the residential sections (except maybe the Kiwibuild ones), then after they were sold started making noises about building a big hotel there. Residents weren’t impressed. There were 141 submissions against and 0 for.
 
What makes this story interesting is that the Northlake residents signed a clause in their sale and purchase agreement where they agreed not to make any formal submission against the developer, and not to negatively discuss any activities by the developer. I understand the developer has been using threat of legal action to silence the residents (aka their customers). All the outcry against this thing is from other Wanaka residents, and no doubt the Northlake residents ranting under pseudonym.
 
I don’t know how prevalent these “don’t say anything bad about us” clauses are, and to be fair they did sign it, but the residents here have been utterly screwed by the developer here.

Very interesting to have developers require residents to never oppose anything the developer does, or even publicly criticise them.

I wonder if they would hold up in court, if described correctly.