He didn't say he was single. One can be a man in his 30s without kids and still not be single, not everyone want to have kids.
And talking about catering to a specific type, Frankfurt and Zürich are way more catered toward a very normative idea of family and individuals A city like Berlin by these standards is deemed less liveable, but some of its flaws is what makes it way more humanly liveable. Also, Berlin has so many areas that are completely different from one another that here you can find the millionaire tech startupper with a villa at Wannsee eating out at Hasir in Kreuzberg next to deadbeat students. That’s more my idea of psychologically livable. But yeah, if you’re into skiing, banking, and fancy wines I guess Zürich’s fine.