When adding a select-field in a suitelet with a source, should running

.getSelectOptions({filter:'filtertext', filteroperator:'startswith'})

really also filter the select-field in place? I thought it only retrieved the options for me to work with, but it actually does filter the dropdown.

let custpage_search_select = form.addField({
                id:'custpage_search_select',
                label: 'Select Export Source',
                type:serverWidget.FieldType.SELECT,
                source: -119  //-119 = Saved searches
            })
let filteredOptions = custpage_search_select.getSelectOptions({filter:'D365 GL Export',filteroperator:'startswith'});
//Here I was planning to add another select field and add the filteredOptions to it.