Here is the exact language:Unless the previous borrower requests a release of liability, the servicer must process the following exempt transactions without reviewing or approving the terms of the transfer.A transfer of the property to a limited liability company (LLC), provided that a) the mortgage loan was purchased or securitized by Fannie Mae on or after June 1, 2016, and b) the LLC is controlled by the originalborrower or the original borrower owns a majority interest in the LLC, and if the transfer results in a permitted change of occupancy type to an investment property, such change does not violate the security instrument (for example, the 12 month occupancy requirementfor a principal residence).This means that as long as the loan was obtained on or after June 1, 2016 and the LLC you transfer it to is controlled by you, the borrower, then the lender must allow the transfer to occur without triggering thedue on sale clause.

What legal instruments exist to prevent this vote from going through?

Title insurance is available when a warranty deed is used, because of the clear title guarantee associated with that type of instrument.  

You are NOT a bank or a financial institution that can keep such instruments in your portfolio for the long term.

But a HELOC is not intended to be a long-term debt instrument. 

Its not just real estate investors, its everyone, myself included who are not huge fans of those instruments.

this was instrumental for me with planning ahead with my tax advisor (my goals, and advise how to do it as a small business owner) 

Also, depending on the state where the property is located, protection against loss caused by mis-indexed instruments.  

That will be an instrumental thing to hold in mind while trying ot determine the best next plays.

The key instrument is the property manager.