Although now we make and eat pickled vegetables because we like the taste, pickling was originally developed in order to enable vegetables to store longer. Calling a serializer "pickle" isn't unreasonable.
It's not unreasonable, but it's still obscure. Calling a time utility Delorean isn't unreasonable, despite also being obscure.
And if i were on the mailing lists back whenever they came up with pickle, i would have told them it was a silly name too.