New feature is that pregnancy advances in real time, instead of once per day. Bug is that it doesn't advance at all while sleeping, like it's supposed to. This will be fixed.
The public builds are much more stable than the testing builds he releases, I'd personally recommend sticking with the public builds.
He's allowed to do what he wants with the money. He may want some nice things. He may want to save up for stuff, or even for a rainy day - you don't get built-in sick days, paid vacation time, or medical insurance with Patreon.
Aside from that, hiring other people would probably be more trouble than it's worth. He'd have to manage them and ride herd on them, deal with people who might miss deadlines or make mistakes, make sure they stick with his vision of the game, and deal with any drama that ensues, and before you know it this might go down the road Breeding Season took.
He also regularly releases content. It might not seem like much, but it is constantly updating. The more any game is developed, the more complex and time-consuming it gets to add new things, because the more code a game has, the more likely it is for new things to interact with existing code in glitchy ways.