I am using the Chinese system to classify tea in this way. The Yue Guang bai would be a Sheng cha but yes it could definately be thought of as a White tea in terms of its relationship with proccessing method.
However, traditionally the content of certain white teas are explicit:
Yin zhen bai hao = one bud 一牙， Bai Mu Dan = one bud and one leaf 一芽一叶. Just to say there are no lower grades of these teas encorporating other material, that is a marketing ploy.
I am of course using the Chinese sytem to classify:
Just as all black tea （this is hei cha 黑茶- not fully oxidized teas that would be Red tea hong cha 红茶）All black tea this way begins as a product of Qing cha 青茶 class- known in the west as WuLong, whereby the leaves are only partially oxidized- then the leaves are given different forms of secondary fermintation making them into Hei cha (Puer Shu cha is the extreme case) but other Hei cha uses a more natural method of Wo Dui 沃堆 for a more natural fermentation- or it is not put through its secondary fermentation and it will go trhough the process later on its own( the extreme case in Puer Sheng cha). By the Chinese system Puer is a category of Hei cha it is designated as- Yunnan Da ye zhong, shai qing de ye zi, which means Yunnan large leaf type, sun dried leaves. It is in fact different than other Hei cha(Liu Bao, Hunan and Sichuan Hei Cha, etc.) because Puer Shu cha (普洱熟茶) and Puer Sheng cha (普洱生茶） are explicitly made into two extremes on the spectrum of secondary fermentation. Most of the other black teas in general falll into the middle of that spectrum. So in the classification system from the Chinese tradition, names and designations come under type- so Puer is under 黑茶Hei cha, just as Wu Yi Yan Cha (Da Hong Pao, Shui Xian, etc.) is under 青茶 Qing cha or Wulong cha.