Update. I received a response from the HR person. She effectively said that she sympathized with my position, but felt that most others in the building did not. I responded with the following.
Thank you for your response. I only saw it just now for some reason, which is why I didn’t respond sooner. And thank you for offering to provide vegan ice cream; I heard that people enjoyed it!
Based on my personal experience, I agree that most people in our building aren’t on the same page. However, I’m optimistic that people would enjoy vegan food at spontaneous events such as this one. If you are open to making animal-friendly changes to staff events in the future I would be very happy to help organize them and take on some of the responsibilities.
Thanks again for being so understanding!
A few minutes later, she replied again, and said that she plans to take me up on the offer. I think this means going forward that we’ll have vegan work events! It’s not set in stone, but this seems very promising to me.
I’d consider this a success. Thanks to everyone here who helped guide me and encouraged me to do the right thing.