I don't mind, and I don't think you're kink shaming I'll do my best to answer this, but keep in mind I can't speak for everyone on this.
The expression is not ideal in my book, but neither would having the woman smiling felt right. An expression of exhiliration or anticipation would have served better, but it's hard to get subtle nuances across in a 3d model. The thing about chocking is the recipient is potentially quite literally putting his or her life in another person's hands irl, and the rollercoaster of emotions, from excitement to fear, lust and trust, well, how does one convey that on an avatar?
Keep in mind, a lot of bdsm has a bit of a playacting element to it. People step into roles of subs, doms, brats etc. so in my mind the female avatar is probably hamming the fear up a bit, to add to the roleplay involved. I admit that this is just me adding context to a still picture, but I have a hard time imagining a real life bdsm couple where the sub is in mortal fear of the dominant.
I fully get that this makes a lot of people uncomfortable. This is niche, advanced stuff. It is absolutely not for everybody. Like I said in my last post in the thread, I do hope future poses will be a bit less niche and have a broader appeal.