Why does Flow allow this unsound destructuring assignment?

Question

https://flow.org/try/#0PTAEAEDMBsHsHdQGcAuAnAlgYxQKC7AHaqgDaaApkgK7QoC6oAvKAN4AeAXKAIwC+AbiA

Flow reports no errors on this code:

// @flow strict
const