I think this point is key. There's plenty of blame on both sides here.

Yes, these kinds of jokes are immature and this conduct was ill advised.

That said, taking ambush pictures of nonconsenting parties and very publicly shaming them shouldn't be your go-to response. I'd say that response was completely disproportionate to the initial crime.

Far better to throw an (in person) "come on guys, be professional" their way and escalate from there. If that's too confrontational for your tastes, go talk to one of the PyCon volunteers and ask them to step in. I think it's kind of ridiculous that they (PyCon staff) didn't get a chance to resolve this issue discretely and had to hear about it alongside however many thousand other people.