No way to disrupt a bias that quickly. Moreover, s/he will never read 500 words from "a low-status member of their own tribe". Here is one classic strategy that gives you a fighting chance.

You have about 30 seconds of attention (hence the elevator pitch metaphor) to present your verbal or written argument. You cannot hope to disrupt their bias in 30 seconds, so you shoot for something else: more attention, maybe some face time. Again, forget about disrupting biases for the moment. You have to become a sales person for an instant and make a difficult sale with the odds stacked heavily against you.

Now your task is reduced to the standard elevator pitch formula:

• a hook (a one-liner that grabs attention),
• a simple but passionate statement of potential benefits to your audience of one,
• a concise and catchy summary followed by a request/offer/promise that is too intriguing to refuse outright.

The details and variations are all over the net and in a bunch of popular TV shows.

From personal experience: busy high-level executives don't read past the subject line of your email, unless they are hooked (i.e. if you are a low-level underling, they don't normally click to open your email), so your hook absolutely must be in the subject line.

Now, suppose you win some face time (your status is temporarily elevated to that of a person worth spending 5 min on). What do you do then? Stay tuned for the next installment of... Changing Minds!

P.S. I have intentionally structured this comment using the elevator pitch format. The first 20-30 characters of this message is all that appears on the right in the RECENT COMMENTS section, so I tried to plant my hook there. Whether I have succeeded or not, we will see shortly -- feedback is most welcome!