This is a very welcome development in the Flask world. It seems that Armin Ronacher (mitsuhiko) found himself in a situation where things outside of open-source projects started demanding more of his time [0] while issues and PRs started accumulating on Flask, Flask-SQLAlchemy etc. You can't really blame him for being overwhelmed by it, and thankfully, in the past day some progress has been made [1] and maintainers are being selected.
It's only a polite fiction that things outside of open-source projects overwhelmed him. Your link itself says that he doesn't want to work on his open source Python projects because of Python 3 taking his motivation.
[0]: http://lucumr.pocoo.org/2013/11/28/emotional-programming/
[1]: https://github.com/mitsuhiko/flask-sqlalchemy/issues/197#iss...