She liked women:

Jansson had several male lovers, including the political philosopher Atos Wirtanen, and briefly became engaged to him. He was the inspiration for the Moomin character Snufkin. However, she eventually "went over to the spook side" as she is said to have put it —a coded expression for homosexuality—and developed a secret love affair with the married theater director Vivica Bandler. In 1956 Jansson met her lifelong partner, Tuulikki Pietilä, known as "Tooti". In Helsinki they lived apart but nearby, so they could meet unnoticed, but this did not resolve the problem that Jansson's mother often came to stay. They found a partial solution by building a house on a small island in the Gulf of Finland, and staying there for the summer. Jansson's and Pietilä's travels and summers spent together on the Klovharu island in Pellinki have been captured on several hours of film, shot by Pietilä.

Hard to say if she was a lesbian or bi or what exactly since it wasn't great to be gay back then, but this is probably commentary to the effect of "Why does it matter if you like men or women?"