According to the RAE, only numbers (un, dos, tres...) or such (medio, tercio, tercera parte...) are partitivos. 'De' is described as part of a construcción partitiva here (lema.rae.es/dpd/srv/search?id=XEVeLzVZaD6CG25cW5), but not as a partitive itself. Personally, I'm not a fan of translating grammar terms because each language tends to describe others using as a model their own conceptions of language and sentence structures. Thus, several English sources describe 'de' as a partitive, while the RAE doesn't recognize it as such. So it may be a partitive, but not a partitivo.
However, note that this question is not the same as the one being discussed in the original thread. There, 'de' was claimed to be a partitive, which is not true in Spanish. 'Un poco de' is indeed a partitive (or a construcción partitiva in Spanish), but not de itself.
Interestingly, other languages closely related to Spanish do consider de as a partitive. The main difference between Spanish and other Romance languages such as Italian or French is that Spanish de in un poco de is a genitive preposition, but French de in Je veux de l'eau or Italian di in Voglio dell'acqua are not so because the genitive case is described as "a noun modifying another noun" and there's no noun to modify in Je veux de l'eau or Voglio dell'acqua (eau/acqua being the "another noun"). That noun is required in Spanish, but not in French or Italian. Actually, in those languages they aren't even called a preposition because a preposition "links", and there's nothing to link in Je veux de l'eau/Voglio dell'acqua.
That's why French and Italian call it a partitive article and consider it more or less as a part of the noun itself, not as a connection between the noun/verb and the noun. So the "object" of I want is de l'eau/dell'acqua, not that de/di connects want and water, as is the case in Spanish Quiero un poco de agua, where de connects "poco" y "agua", thus being a real preposition rather than an article. That's what makes them essentially different, both sintactically and morphologically, and there lies the difference between a 'genitive case' and a 'partitive'.