She withdrew not because of afraid facing SST, it's because she's injured. Left achilles this time. Similar injury she suffered two years ago, albeit at that time was on her right thigh, instead of her left leg
Did you know you can quote more than onces on 1 post ?It happens for so many years ago, the prize money gap between the men's (ATP) and the women's (WTA) side has improved somewhat, the gap would have bigger had not do to BJK not winning the in famous battle of the sex match, which she won in straight sets. So the prize money issues is not new, it happens long before the open era
Anyway it looks like she has an ankle injury, as the article says.
If she is really badly injured or if she is too scared to play is only speculation.
We don't know that so I give her the benefit of the doubt. When she said she is too injured to play then she is.