Passive-aggressive is not only a silent treatment. It involves any behaviour you take in when you really don’t want to take in and produce a long or shorter term resentment. And after that you give an aggressive response even when the timing is not appropriated.

Of course you were reluctant to have pics taken. You said no. You said no many times. And assertive way to be is saying no one time and act in consequence. No is no.
But you yielded, not only once but several times. This is passive. It all creates a situation where you felt uncomfortable from now on at this same situation.

Them, you sent a message to them putting the focus on their behaviours and how much it bothered you. Kind of ultimatum to them. Defending your rights but in an aggressive way. You didn’t take into account what you could have done in a non assertive way to get this behaviour from them.

I’m gonna be honest. If they push and push with like in this case, about having you in the pics, I would also feel bothered because they showed very little comprehension but sometimes people are like that. Some people lack of the ability to understand the other person. Not everybody is gonna understand what social anxiety is. So, you will find people like that. Do they have bad intentions or do they did it on purpose. I don’t know it. Depend on others behaviours they may display within the relation.
So, as there’s that possibility that they neither understand such a thing and don’t give the importance you give. I’m focusing on your responses.

What I would’ve done? Not “should” Noone is forced to do anything other than accept the law. I prefer to treat in in a different way.
Hypothetically. I would’ve done just the very thing I had felt more comfortable with.
It has been already say by other members here.
I would left myself to take a pic by previously saying to them. Girls, I never like to have taken pics of me but I’m gonna participate in this one and from now on, I will be only the photographer.
That’s it.
So you yield only up to the point you may feel confortable with. It’s a matter of reaching a consensus. You give something to them but at the same time, you sat a boundary.
When they push again, you repeat like a broken record: Remember girls, I’m your photographer.
That’s all. If they keep their pushing you. With this and other things you feel bothered by and you treat it in the same way but you get no comprehension. I wouldn’t meet them anymore. Unless, they contacted me and apologise. But, don’t contact them with reproaches. That’s not gonna be useful as you already stated in previous posts.

When interacting to people, I try to consider also, not only my reasons behind a behaviour but also the reasons behind others. It’s very important to see the other like an equal. And in the same way you take into account circumstances under a certain behaviour from yourself, it’s also suitable and worthy to consider the other part’s circumstances.

Are these group of friends extroverts?

In any moment, I’m encouraging you to go on with these group of acquaintances. Ok. You have the right to pass page with them if you are not comfortable with.
I’m only giving you a way I may have interpreted things and how I would have handle this particular point about the pics taken. Ok? I understand you may feel uncomfortable with them for different reasons you explained before.

I also understand why you may feel attack and defensive. It’s common in people with our issue as well as, takin when we don’t want and then, overreact.

By the record, I’m your age 51. That is, we are 41 since now 50 is 40, 40 is 30. Things have changed and we still rock. 😀👍