'any' has always been intended as an escape hatch, so no abuse here [1]. The type representing the set of all possible values (the top type in the type lattice) is 'unknown'.
The widest possible function type is `(...args: never) => unknown`. This is because parameters are contravariant, and `never` is the bottom type. Using that type works in the author's example[0].
I've got an issue open about TypeScript's provided `ReturnType` type which is somewhat related to this[1].
[1] https://www.typescriptlang.org/docs/handbook/2/everyday-type...
[2] https://www.typescriptlang.org/docs/handbook/release-notes/t...