Do you feel the same way about people that want to prevent chain stores or Walmarts from opening in their neighborhoods? It's something like that...
Oh the Urbanity! recently did a (7m) video on this, 'The Problem of “Neighborhood Character”':
You are right! It looks like he might not give a crap about the actual financial "hit" from depreciation of his house as much as he worries that if the prices do go down, Atherton will become more affordable, and that to him is probably a massive problem.
Solution is to just not give local towns such strict control. Otherwise there is truly no incentive to allow building like this
And it's false in any case according to some of the research I've seen. It's housing. For people. Not a sewage facility.
You most likely will never get to that point if you aren't greedy and always look for your personal advantage.