[nlh]

I am DEFINITELY not a lawyer so as others have said, talk to your counsel about this.

Having said that: The SAFE is a contract. The contract states in the first line "in exchange for the payment by [Investor Name]". If the investor doesn't make the payment, then the contract can be voided for cause. You should be able to give the investor notice that you are terminating the contract for cause (lack of payment).

But again, talk to your lawyer.