Exactly. So?
If this is adopted, (and there is no reason to believe it won't, it did before!) it excludes an entire group of veterans from receiving benefits from exposure to Agent Orange depending on where they were standing, not how they were exposed. (see reports relating to AO contaminants and shipboard evaporator distillers. Pay particular attention to the reports of concentration and enhancement of the Dioxins by copper during the distilling process.
Then note the facts found by the National Academy of Science's Institute of Medicine and Center for Disease Control's reports. There are MORE Dioxin related diseases found in Navy Vietnam veterans than were found in land based services.
This can of worms is gonna blow-back. I hope I survive my Leukemia long enough to see us acknowledged.
But I probably won't.
It sounds like you are intimately and emotionally involved in this, so I will not presume to know more than you. However, as I read the Federal Register attachment from above, it looks like this is a very narrow definition used for purposes of determining who may be presumed to have been exposed to Agent Orange. I see no indication that others who do not fall under the definition may not also be determined to have been exposed to AO through some other adjudication process.
Certainly, this will not revoke Senator McCains status as a Vietnam Veteran.
Thank you for your service and prayers for your current battle!