Make PageListSelectMultiple fields not sortable

[adrian]

Anyone know if this can be done via the API?

I feel like there should be an equivalent of the 

$field->setAsmSelectOption('sortable', false);

that works for PageListSelectMultiple fields, but looking through the core code, I can't seem to find anything.

I guess I could remove the InputfieldPageListSelectMultipleSortable class with jquery, but I feel like there should be a better way.