There is a problem with silicon-based life. Silicon is not as nearly versatile chemically as carbon is. It is highly doubtful silicon can sustain any meaningful biochemistry -at least, not by itself

These statements are all true... on Earth. Plenty of reactive silanes are possible. All known biochemistry is based on carbon, so of course silicon is not going to catalyze many biochemical reactions. But carbon-based reactions do not go so efficiently in the cold... Iron chemistries might have gone wild on Mars. Why not metal-based life (lots of metals form strong alloys)?

Carbon itself is highly unreactive. This is why pencils and diamond rings are allowed on airplanes. It needs bonded groups such as amines, hydroxyls, thiols, etc. to get any meaningful work done. Carbon is just the backbone.

We simply haven't tried every possible chemical reaction in all possible environmental conditions to know which reactions might be "spontaneous" on other planets. We can sure try and guess. However, chemists are surprised every day by reaction kinetics, behaviors, and mechanisms here on Earth. We still don't understand chemistry that well. So why do we need to stifle ideas of how things might evolve on other planets with vastly different experimental conditions?

We should be looking closer at Venus instead... it's nearby, lots of strong chemicals and lots of heat make for an intriguing place for reactions to take place. Moving far away from the Sun is misguided if we're looking for interesting chemistry...