The Issue is when a Rule is invoked that uses the Disabled Checked box. The font does indeed become light gray and this is within the default style of Nintex.
This is true even if a font color is selected in the Rule. So the font color in the rule is not being applied.
Attaching the Test list created and the form created with the rule of date control disabled if not(New Mode).
This setting can be overwritten only in controls that are single and multiple line text since the controls have a font setting.
So why is there rich text formatting (font, font size, font color) in the Add Rule functionality and it does not work???? This is an Accessibility issue that must be resolved.