I will try my best to take both sides of this ‘dispute’ into account as I present to you how this is, in fact, not an argument of any sort but rather ignorant hypocrisy. To lay the ground work for understanding who 'Zwarte Piet' is, the following facts need to be established:

1. Originally, in medieval iconography Sinterklaas (Saint Nicholas) was presented as taming a chained demon and the equivalents of those demons have been redeveloped as dark-skinned humans during the 19^th century in the likeness of Moors. 
2. Moors, if you don’t know, refers to the Muslim inhabitants of the Maghreb, Iberian Peninsula, Sicily, and Malta. This is equivalent to the modern day ‘Arabs’. I am a Moor.
3. He appeared first in 1859 in a book by Jan Schenkman, a teacher based in Amsterdam.
4. Historically, from the 1850s to the 1950s, racism was full-blown in a ‘biological argument’.
5. Blackface is a form of racist ‘make-up’ worn by non-black individuals to racially stereotype and dehumanize an entire ethnic group.

So, after talking to three Dutch young adults of relative social awareness about how they can still justify blackface in the name of a traditional costume, the following statements were made:

1. It’s Dutch heritage and it’s not right to just take that away; it’s not like there is much of it left with all the immigration.
2. It’s just a children’s character and was never considered to be racist until people outside of the Netherlands started recognizing it as such.
3. The whole anti-Piet movement is just taking the fun out the festivities.

So just to sum things up, blackface is being ‘justified’ for a traditional costume that is deeply seeded in Dutch colonial heritage, but it should be fine because there’s not much other than this character that can be attributed to Dutch tradition?

Blackface is racist. Racism is racism regardless of the ‘circumstance’. Your traditions can be racist and they will need to change.