For anyone interested, I got the following response from Hawaiian regarding transferring HawaiianMiles to Marriott Bonvoy:
Aloha,
Thank you for your follow-up.
I have received an update from our Support Team, and our deepest apologies for all the confusion.
This process they advised does not go live until September hence the reason it was not yet cascaded to our agents as to why they were unable to assist you with further information. With this, I again apologize.
For now, the Bonvoy icon has been unpublished from the redeem page and the Marriott Bonvoy Partner page is back to normal.
We appreciate the opportunity to respond to you.
So apparently the page went up too early and they took it down due to my inquiry. They will presumably bring it back soon and the link will lead to somewhere useful. As of now, the link in my original post leads back to their old partnership page.
I followed up requesting the transfer ratio, but they responded that "This has not yet been cascaded, as has not yet taken effect. Unfortunately, I am unable to provide this information at this time." If the transfer ratio will be the same as the 3:1 Bonvoy to Miles ratio in reverse, the current 80,000 offer would be a great way to replenish Bonvoy Rewards with 240,000 points! Even at 1:2 it would still be good value at 160,000 points.
We'll need to wait and see.