This argument deserves much more recognition than it gets because 1. it's at this point still empirically true, we have not observed non-organic sentient life and more importantly, because not Searle but everybody else employs 'magic'.
Searle's point is simple. Computation is subjective. Electricity flowing through a machine doing complex things is just a physical process like anything else. You (the sentient observer) classify that physical process as meaningful, but a computer is no more 'computing' things than a falling pen computes gravity.
So sentience really is related to physical agency and sensory experience in the world, which creates conscience in organic brains. That doesn't imply complexity or intelligence or understanding. Syntax and Semantics are different things. Your pocket calculator processes the syntax of mathematics, but it does not understand the semantics of mathematics. A compiler processes symbols according to rules, but it does not understand the meaning of the computation, it has no cognition. It might be very good at what it does, but it has no capacity to understand. That's the essence of the Chinese room, and it's still a convincing argument.
An even stronger point might be made, namely that sentience actually limits intelligence. That it requires a degree of slowness and introspection that is unsuited for fast decision-making. For a fictional treatment of this, Blindsight by Peter Watts is an excellent read.