Oh.
Probably worth pointing out how, in my quote above, the Cassini team are using several flybys for these measurements. If you catch Titan at different distances from Saturn, you get a measure of how it deforms under tidal strain: that not only gives you density-gradient information, but an idea of the viscoelastic properties, too.
That second modality is also helpful in differentiating liquid from solid.

Grant Hutchison