AIBU to think WTF were the parents thinking?

[JakeyRolling]

DS (7) had his school Halloween disco last night.

Amongst the usual questionable costumes (Squid Games guards, tiny cheerleaders outfits Etc… The kind I wouldn’t do and I can’t understand why a parent would but not inherently problematic) there was one kid in a Santa outfit with a scary pointy “blood” splattered mask and a stabbing knife. (The mask is similar to the pic)
Quite apart from the fact the school has a “no masks” policy, this was for the P1-3 age group so the oldest kid was no more than 9 and therefore many kids are still believers.

DS is autistic and was a bit upset by it and we had to explain several times it was a costume.

AIBU in being pissed at the parents?

I like how in the US they often wear general fancy dress/fun costumes for Halloween. I prefer it to little girls with zombie make up on etc.
In Modern Family Mitch was spiderman one year and Mitch and Cam were Harry and Meghan once.

It's catching on here too with teenagers, based on photos of costumes I've seen this year.

Surely that's appropriate for carnival, not Halloween. We don't have to import all the commercial blurred lines blandness.

I'm saying I like it, not that we must "import all the commercial blurred lines blandness."
It's OK to like something another country does!

What do you mean by 'carnival'? That sounds v American to me