Looks like the dress code intends to make off-limits what is commonly seen as “major” types of inappropriate dress (e.g. showing more underwear than waistband, covering one’s face or ears (other than religious observance), accessories that could be weapons) but not take the responsibility for more “minor” or less agreed upon issues (length of skirt/dress/shorts, hats, sleeveless shirts, etc.).
There could still be issues and controversies dealing with the content-based restrictions:
For example, does a T-shirt that references “beating” or “crushing” a rival sports team come under the first prohibited category in the above list? Does a T-shirt with a Confederate States flag on it come under the third or fourth prohibited category in the above list?