Constraint propagation using Projection rule

Question

I've found this example of constraint propagation using projection rule

We have

C = { x1 ≠ x2, x1 ≥ x2 }

< C; x1 ∈ {1,2,3}, x2 ∈ {1,2,3} >

They say that applying propagation rule, does not give any simplification.

I'm not sure why this is the case. Shouldn't we get?

< C; x1 ∈ {2,3}, x2 ∈ {1,2} >

Other steps in the example, make sense that to me, e.g.

< C; x1 ∈ {2}, x2 ∈ {1,2,3} >

produces

< C; x1 ∈ {2}, x2 ∈ {1} >