Let's assume you purposefully crafted the email or app to break the code autofill built into iOS.

I think you'd end up confusing users. Most people will go to their email expecting to see a verification code in big bold type. If you make the code less obvious, they'll get frustrated ("I came here to get a code, why am I now doing something else?") It's awful UX at a particularly business-critical moment.

And this is all assuming Apple doesn't see through your ploy and just reject the app.