> If options & futures are more liquid than the underlying, someone will be tempted to nudge the underlying.

This is a weird statement. Why would liquidity matter here? As a point of reference there are generally two types of options: (1) options that depend directly upon the underlying, like a Tesla stock option, or (2) options that depend indirectly upon the underlying, like options on S&P 500 index futures. The liquidity in category 2 is normally tiny. Cat 1 normally has far less liquidity than the underlying.

Why is the adjective "more" important here? Even if less, the opportunity to profit is still good, assuming that one chooses the path of market manipulation.