Are there problems in my partial assignment patent case?

I am being asked to partially assign my US patent to a Delaware LLC in return for an ownership position. I am only a co-owner of the patent and there is one other co-owner. He is not in agreement but the LLC is willing to just take partial assignment from my 50%. I negotiated a performance type clause. Meaning if they sat on patent and made no forward momentum that the IP would revert back to me at a certain date. I am supposed to get language incorporated into assignment agreement stating such and the LLC will also incorporate similar language into operating agreement. The patent has never been assigned in the past. After researching on WIPO website I found the following: What is Assignment? In contrast, an assignment is irrevocable. An assignment involves the sale and transfer of ownership of the patent by the assignor to the assignee. This transfer of ownership is permanent and irrevocable. Just as when any other asset or property is sold, its sale results in the former owner being permanently divested of that ownership." Now I am concerned that the death clause provision would not stand up in the court of law, or in patent law. Please help me understand to see if my concern is accurate.