Not true. The math don't math.
There are estimates to be between 1 and 2 million prostitutes in the US. They're not all women, but that number is so far above the 50,000 trafficked women in the article that it cannot account for the discrepancy to parse out genders just by applying common sense.
*Some* prostitutes have been trafficked, but to be classified as a trafficked prostitute you have to meet two criteria.
1. A third party has to financially benefit from your sex work. In other words, there has to be a pimp involved.
2. You have to have been forced, coerced, or manipulate into selling yourself for sex.
It's not either/or. You gotta be able to check both those boxes.