Yes, this is how it works because Porkins ability occurs after the token is assigned. He CAN choose to remove both tokens, but based on my understanding of the rules you cannot keep jamming him in the same fashion as you could with an effect like Captain Yorr. Otherwise, you could, in theory jam Porkins until he blows up from the damage. Then again, Yorr's ability and Porkins ability are both optional anyway, so the player may deem it better for them to just accept the stress, given the situation. Unless its an interceptor, I'd probably elect to take the stress as opposed to having 2 stressed ships from the same effect.
The Jam action goes off and you pick how many stress tokens you are going to give the target ship. That stays fixed. AROO comes into play because of similar situations, such as elusiveness (You hit me with 2 damage so I choose to take 2 stress tokens at the same time and make you reroll 2 attack dice. AROO prevents this)
You pick how many to assign with Jam, Porkins triggers and removes 1. You can't go back and add more because of AROO.
In the case of Porkins, he gets one Opportunity for each stress token, so he can remove both if he chooses. AROO still applies because each stress token is a separate opportunity for his ability. If he activates it twice, he has to resolve his ability twice and risk taking two damage. With Elusiveness, the card specifically says one die for one stress, you can't use it if you already have a have a stress token anyway. If the card text allowed for two, then it could work twice. The Text for Jam says assign stress tokens to a ship until it has 2. I was agreeing that it didn't work for Porkins. Given the Yorr situation, I think it requires an additional FAQ to outlaw it, because the text says "until it has a maximum of two tokens," not "Assign it up to two stress tokens." These are not the same. Previous rulings for Yorr have stated the stress pull happens so soon that other abilities that rely on it don't occur, such as Soontir's focus token. I also mentioned how this is probably a bad strategy in that, if it works the way it seems, it stresses two ships.