This is not interesting in the way that "DNS parsing is turing complete" is interesting. Nobody can send you a unicode file and make you run an infinite loop or whatever. Within Unicode is defined a DSL used internally by the library implementers to define some business logic, like most DSLs it is turing complete. Anyone with the ability to make you run their rules file already has the ability to make you run arbitra…
> The person who specified this most likely was aware that this is turing complete and it's the rules author's responsibility not to write infinite loops
Software developer’s job description: prove that this instance of the halting problem you’re being paid to work on today is decidable