Yeah, that's on the customer. If you write that you want a bunch of fuckin cherries then you're getting a bunch of fuckin cherries. Now go eat the pile of cherries you ordered.
I don't really care for what, if you are requesting something from someone you don't know in a way that's intentionally stupid or roundabout, you need to be prepared to get exactly what you asked for.
Fast food doubly so, they give no shits. Ask for a burger but hold the burger? Expect an empty wrapper.
Eighty-six is slang meaning "to throw out," "to get rid of," or "to refuse service to." It comes from 1930s soda-counter slang meaning that an item was sold out. There is varying anecdotal evidence about why the term eighty-six was used, but the most common theory is that it is rhyming slang for nix.
Just to throw it out there, 86 is also used in the film industry (at least in LA) meaning to cancel or get rid of something. It's very widely used across the industry. I don't know of any other slang that is shared between restaurants and film though.
Even if he had written "86 the cherries" they probably never heard that term. I'm about to be 40 and I only know it from Loony Tunes and other cartoons stereotyping a 1920's mobster.