That's the part that seals it. Everything else could be (implausibly) explained away as an accident of ignorance and bad taste, but that part can only exist through a stereotype.
Colors are extremely important. Saying that if changing the color of a specific part of a widely-known and emotionally-charged symbol makes that symbol not longer valid is, frankly, a statement utterly ignorant of the way symbols work.
For example, if these cupcakes had the Italian flag on them instead of little faces, we would rightfully say that they're meant to channel visual language that suggests Italy. If you came in here yelling about how if we changed the green stripe to blue it would be the French flag instead and therefore the cupcakes were clearly not Italian, I don't think your argument would be valid.
These cupcakes are clearly channeling blackface imagery. You can take issue with how big a deal that is if you want to, but you can't take issue with what they are just because changing a color negates the symbol. Someone chose to use pink. That choice has repercussions.