Why did he make that decision? (spoilers)

I just watched it on vimeo (thanks to this board); but I don't get why he decided not to help his mother. He had wanted to since he was a child. He knew his mother was good to people, and that he would be able to make more time for himself. (I get that he didn't help his sister because she just squandered her time).

I suppose the woman in the garden was like Eve: a temptress to the original golden son Adam. She tells him his mother won't mind that he is furthering himself at her expense since she didn't ask for his sacrifice. But now he has no mother; sure he has plenty of trees and profits, but he knew he would make enough money for himself anyways. Was he mad at his mom for propagating the lie that you could only go once to the elders, and the gatekeeper for saying he could only stay 12 hrs?

The elder told him to never be sorry. He didn't seem sorry at his mothers' funeral - just matter of fact, yet lavished a huge amount of money on the funeral. Had he lost his soul? Or found his true passion?

Were the trees really that important to him? The viability of his original tree plan seemed ill-conceived? He said the venture didn't work when people wanted trees to replace artificial air; but what was his venture proposing again...a nice sound in the wind?