Why is $y=Re[\rm{sin}^{-1}(x)]$ flat beyond $z>1$?

Question

In the real domain, $\rm{sin}^{-1}(x)$ is undefined for $x>1$ but in the complex world WolframAlpha produces a flat graph for large inputs:

Throwing in some test values explicitly, wolframAlpha tells me $Re[\rm{sin}^{-1}(10)]=\frac{\pi}{2}$ and likewise for other large inputs.

I was intuitively expecting extended complex solutions to lie in curves. Why is this function constant for large inputs?