Sure, but that's basically my point, or at least the point I thought I was making. Chemosynthesis can provide enough energy for bacteria, but to have anything much larger than bacteria you'd need a bigger source of energy, such as high solar radiation, right?

Right.

Which is why nobody expects other kind of life on Titan except bacteria-like and virus-like, but there is a non-null probability for the existence there of this kind of life, which is also the only kind of life that had existed on Earth for billions of years.