Can oa_section_ref field be hidden or do i need entityreference_prepopulate?

In my prior experience with entityreference_prepopulate, putting a parameter like oa_section_ref in a node/add URL was enough to hide the oa_section_ref autocomplete field, assuming you checked the right box on the field config.

In OA2, the oa_section_ref field is a select list by default. but i generally don't want users to be able to change the section they are assigning their content to. Should i form_alter to hide that field, when the parameter is present? Should i install entityreference_prepopulate and switch to using an autocomplete widget for those fields?