There's no "security considerations" section in the document, but I hope you'll consider writing one.

Creating a new execution context in which JS executes is certainly interesting from a security standpoint. I'd like to see explicit discussion of the origin in which that code executes, and the privileges it ought to have. It would also be helpful to have a list of considerations that other authors should consider when determining whether a particular feature ought to be enabled for Worklets' "reduced API surface".

Likewise, how is the Worklet's script fetched? What Content Security Policy directive ought to apply? Should Worklets be available to non-secure contexts? Etc.

Thanks!