It sounds like the engineer may have little/no experience with concurrency; a lot of folks (myself included) sometime struggle with how various systems handle concurrency/parallelism and their side effects. Perhaps this is an opportunity for you to “show not tell” them how to do it.

But I think my point still holds—it’s not the tool that should be blamed; the engineer just needs to better understand the tool and how/when to use it appropriately.

Of course, our toolboxes just keep filling up with new tools which makes it difficult to remember how to use ‘em all.