sort {rand > .5}

That's a bad way to scramble text, because it uses a bad method of performing a sort. The documentation makes the following point:

The comparison function is required to behave. If it returns inconsistent results (sometimes saying $x[1] is less than $x[2] and sometimes saying the opposite, for example) the results are not well-defined.

The usual definitions of not well-defined include dumps core and fails to terminate. It might work, but only by luck.