Elon has said this on conference calls. My interpretation of what he said is it in not in the financial papers you signed but rather in his own estate planning. I personally think this is moot.
Tesla Motors calculated the "worst posible case" for the financial offerings and if they can cover this. As a business person you do calculations of "best case", "worse case", and "realistic" before you initiate major business decisions in a company. Managers do this for short term ~1 quarter to 1year, medium term 3-5 years and longer term 10 years. Elon has a long term plan to be part of Tesla until he he completes his goal to change transportation. He has calculated the risk and his likelihood of success and stands behind the company.
If this is so important to you, ask him on twitter. I know it sounds like I "drank the cool aid", and that is true, but I have also heard Elon speak many times, and I do believe he is sincere.
I also think if anyone is so worried about the difference in 1.5% vs 2.5% financing, that they really need to question the CEO about his own estate planning, perhaps getting a Model S right now is not the right financial move at this time. Wait 2-3 years to see how the "resale market" holds or wait and buy Gen 3 with cash.