I emailed 3 different Marriott addresses for the Platinum challenge. Got responses of Gold challenge, Silver challenge, and no challenge. Decided to call and was planning on trying 3-5 different times before accepting accepting a Gold challenge. However, on my first attempt, guy started off saying that they usually don't offer Platinum to new members without a lot of history but eventually did offer the Platinum challenge after I said I was Platinum with Starwood.
Waiting on email confirmation and status change to make it official
Called the standard customer support number on the website: 1-801-468-4000
Good luck to anyone else who tries