Sam: I believe there’s a difference in Tznius for a woman to be seen at one’s own event, mainly invited guests for a limited time versus posting a photo online for a much broader audience for posterity. That’s where “Hinei Be’Ohel” comes into play.
Also, at an event one can’t “ogle” without looking weird and the subject is likely “a moving target” whereas online people can stare for as long as they wish without any oversight.
It’s unfortunately also possible to edit photos or add critical comments and forward it. Hopefully not the norm but still a possibility and reason one might not want her photo out there.
And it can be argued by say someone of the Ger Chasidus that because of Tznius couples shouldn’t be seen together at all, which would preclude their own wedding, but perhaps not in photos afterwards.