Again, my personal opinion, not a CF opinion...
I see this the same way as holding a door open for someone. It's polite, it makes people happy. It's not necessarily a social norm. But it's also not mandatory.
Just like holding a door open for someone about to come through it, as a suiter I'd keep my head on until I'm out of the way. I CAN take my head off. I CAN let the door close. I choose not to.
Likewise, I also cannot expect everyone to hold open the door if I'm about to pass through. I'm glad when they do, but if they don't, I'm not going to kick up a fuss. Similarly, if a suiter walks around with their head off, I presume it's for a reason. I may prefer it if they had kept their head on but I'm not going to tell them off for doing so.
So, in short. I'd like to see people holding doors open for me. I'd like to see fursuiters with their heads on. I hold doors open for others about to come through. I keep my fursuit head on. I don't expect people to hold doors open for me. I don't expect fursuiters to always wear their heads.