Regressive response, credulity-straining assertion

The filing also read, "In a regressive response more suitable for reality television than a white-shoe corporation in the 21st century, plaintiff was advised that these other comparator females may wear what they like, as their general unattractiveness rendered moot their sartorial choices, unlike plaintiff, whose shapeliness could not be heightened by beautifully tailored clothing."
After rejecting a complaint and an application to be transferred, she was eventually moved to a new branch, she was reprimanded for failing to recruit new customers.
"The purported reasons for plaintiff''s termination included that she failed to meet the required new account opening quotas, in addition to the credulity-straining assertion that her clothing choices were ''inappropriate,''" the suit said.
"Are you saying that just because I look this way genetically, that this should be a curse for me?" she told the Village Voice, which first reported her case.

Please explain to me the emboldened parts.

Source : http://www.expressindia.com/latest-news/Woman-fired-by-Citi-for-being- hot/628849/