The way I am reading (now that I found the exact verbiage) is that even if a seed and crop has been found harmful they can continue to sell those seeds and crops, as you stated.
Sec. 735. In the event that a determination of non-regulated status made pursuant to section 411 of the Plant Protection Act is or has been invalidated or vacated, the Secretary of Agriculture shall, notwithstanding any other provision of law, upon request by a farmer, grower, farm operator, or producer, immediately grant temporary permit(s) or temporary deregulation in part, subject to necessary and appropriate conditions consistent with section 411(a) or 412(c) of the Plant Protection Act, which interim conditions shall authorize the movement, introduction, continued cultivation, commercialization and other specifically enumerated activities and requirements, including measures designed to mitigate or minimize potential adverse environmental effects, if any, relevant to the Secretary's evaluation of the petition for non-regulated status, while ensuring that growers or other users are able to move, plant, cultivate, introduce into commerce and carry out other authorized activities in a timely manner: Provided, That all such conditions shall be applicable only for the interim period necessary for the Secretary to complete any required analyses or consultations related to the petition for non-regulated status: Provided further, That nothing in this section shall be construed as limiting the Secretary's authority under section 411, 412 and 414 of the Plant Protection Act.
Here's an idea! Have the company (that knowingly created) compensate the farmers for their lost revenue. This is the same company the said DDT and agent orange was safe.
Not to get too off topic.