Got a response to my email / question.
Dear Garrett, thank you for reaching out with this excellent question. Here is a first response, and I will work on an update to add to our website, as I expect many other purple tomato fans have similar questions in mind.
One of our drivers with the purple tomato is to show that it is not so different from any other tomato you grow - it has 3 genes added to make it purple, added on top of the 30,000 genes that all tomatoes have (and, of course, there is a lot of diversity in those genes and the total number, between varieties!). Therefore, the response should look similar to this question asked of any other varieties you grow (Celebrity, Early Girl, etc.).
Accidental crossing: This is low-probability, as tomatoes mostly self pollinate. It is possible, and the risk would be similar to other tomatoes you grow. It will not escape notice, because a contamination will result in purple fruit - if this happens undesired, these plants can be destroyed.
Saving, breeding, sharing: This is a strong tradition among many gardeners, and we support people growing the purple tomatoes in similar ways to any other tomato. There will be limits to this, and we will make them clear when we are able to share the seeds.
This answer depends on USDA granting regulatory approval.
Here's what to expect:
1) It will be illegal for the seeds to go outside of the US, as we anticipate approvals first in the US and not in many other countries.
2) We will stipulate that it is fine to save seeds, breed, grow fruit for home/community consumption. We encourage this, and look forward to learning of people's successes!
3) We will require acknowledgement that people who wish to develop commercial activities (selling fruit, selling seed, selling transplants, breeding new varieties for commercial purposes) contact us. Cathie Martin and her team invested so many years to develop this amazing tomato, and we want to make sure that she can continue to develop her vision for this tomato. We encourage this, and look forward to product commercial partnerships to bring purple tomatoes to our fans.
Thanks for your interest and best wishes,
Seems like breeding / seed saving may be allowed depending on how everything goes. Seems to be a few stipulations here.
I myself wouldn't mind contacting contacting them before selling seeds / breeding commercial varieties prior to doing anything. They put quite a bit of time and money into this.
This is a pretty big forum, it should be easy to notice any contamination, but I would be sure to keep these isolated from other varieties just to be on the safe side.
If you don't isolate these, make sure that you notify anyone else that you send seeds to that these were grown nearby to prevent any issues.
Even if the other person doesn't mind contamination, they could see purple genes pop up and send it to a friend overseas.
These are GMO traits, there are more legal problems than the standard stuff. Please don't try and be sneaky about this, you could get in a lot of trouble for sending unapproved GMO seeds elsewhere.