This is to protect them in case the market fluctuates among other reasons.

Depending on how your taxes are set up, a CPA could recommend forming an LLC or an S-Corp (from a legal standpoint, they offer identical protection, but could offer differing benefits from a tax standpoint).   

If Airbnb is more concerned with me  protecting my business than they are with the 5 properties doing over $600k in annual business with them, I can live without them.

Talk to an asset protection attorney in your state to learn more about why.  

If you don't have an LLC set up and are using an umbrella policy to protect yourself from liability do you want a policy limit greater than or equal to the amount of equity you have in your properties or greater than or equal to the property values?

-Recommend the receptacles in the kitchen, bathrooms, and exterior are GFCI protected.

I am going to guess you are doing this for more not less control of your life so maintaining control of your cash would be essential for growth and protection against unforeseen conditions. 

You get the worst return on your cash but have the greatest protection against market turndowns in terms of the asset protection.

If the purchase was 100K and rehab is 40K and the ARV is 200,000 then there is plenty of equity to protect the investor.  

Offers asset protection if someone tries to sue