1. The person on Twitter doesn't exclusively ask Ryan about the business. He specifically asks how he spends his day. Even if the asker wanted to know more about the business and less about his day, Ryan's response is appropriate given how the question was phrased.
2. Ryan does talk about which business activities he focuses on. He specifically mentions how he used to handle newsletters, wireframes, support emails, and marketing plans but now focuses on strategy, product, and team communication.
3. Ryan is a CEO of a venture-backed company and people, including ones on HN, are sometimes interested in the lives of people like him, both the personal and professional aspects. The personal details he shared helped me understand how he's able to maintain work-life balance, notwithstanding the demands of a CEO, which I find personally useful.
4. As to your complaint of him specifically mentioning his iPhone, one of the other commenters put it best: "Because his identity revolves around the brand of his phone and he's just begging for your validation. OR The post is full of specific details and he owns an iPhone."
If you want Ryan to be more specific, you could ask him on his blog. But I think it's unreasonable to expect that Ryan should have had the foresight to be more specific, and then subsequently criticize him for not being specific.