Users no longer on account or shared to a sheet, should not appear in dropdown for Assignees

Netra

Outside of filtering for running reports - if you are using a sheet for project tracking purposes only (as I do), there is no logical reason for the names and emails of former users or people who don't have sheet access to appear as Assignee options. I kindly request that this is addressed by Smartsheet. This shouldn't require a filter, especially if filtering only works on sheets used as reports. Thank you.