Interesting theory, and plausible, but... why now? Is he hoping to influence the upcoming election? Just what does he get out of it besides publicity?
To the best of my knowledge, a Kennedy is not running for President or VP. How would this influence the election?
As far as publicity goes, put yourself in this man's place. If you were JFK's only living son, wouldn't you want the world to know? I would. If he is JFK's son, as I suspect, and if he was after money from the Kennedys, he could have gotten enough money to live on long ago and could have been enjoying a wealthy life ever since. He didn't do that.
Regarding the " why now" part, I can think of a few possibilities. First of all, he is close to the age of JFK when he was President. The resemblance is clear, IMO. Maybe it wasn't as easily seen when he was younger, so he felt that the time was right to try to make contact with the Kennedys, which he has done.
Maybe he didn't contact the family while JFK, Jr. was alive or in the years when his untimely death was in the headlines out of respect for John.
Maybe Mr. Worthington's mother (or perhaps a husband who raised Worthington) died recently, freeing him to tell his story without causing her any embarrassment or hounding by the press. Maybe she only recently gave him information or documentation regarding his paternity such as support checks from a Kennedy accountant, or letters from JFK about his baby son. I don't know. Time will tell us what he knows and how he came to know it.
The best possibility, IMO is that maybe he wants to get to know his half-sister, Caroline, his uncle Ted, his plethora of Kennedy cousins and the rest of his remaining paternal family while there is still time on this Earth. As an adult who has made contact with blood relatives, I understand that a person takes a huge risk of rejection under ordinary circumstances. Imagine being rejected by the Kennedy clan and all of North America and Great Britain reading about his humiliation in tabloids.
I wish him the best and hope he is who he thinks he is, the son of JFK. I don't know if he has children, but I hope he has a son to carry on the direct lineage.
Maria