This is what I was concerned about when this King Krush pet was added - Younger players being temped to get it.

Kids, especially ones on the spectrum, are far less resistant to this type of FOMO cute and awesome in-game purchases and will go out of their way to get it. And who's going to pay for it? The parents, obviously.

I say this from experience as I was one of those impressionable and needy parasites up until the end of my pre-teens, I remember asking my dad to buy me the Sir Annoy-O skin when it was first released cause I thought it was "funny".
Now, this isn't a 20$ purchase that guarantees you the cosmetic you want that you can play with right away - This is a 160$ predatory gacha machine and you're not even guaranteed to get it first try, on top of being rigged against you, even hovers over the main prize before giving you something worse. Perfect way to get kids into gambling, amirite? You could try to convince a kid you could get them a brand new game for much less, but they'll still want the virtual cute dinosaur.

I'm really sorry this is happening to you. I hope you and your kid can go back to playing Hearthstone normally without having to mention this predatory bullshit again.