Allow autofill in "User Picker" field without allowing request sharing

When creating an approval flow, you often need to allow the customer to choose an approver from a list.  This is where the User Picker field comes in.  As the customer starts to type an approver's name in the field, the field autofills potential approvers' names.

However, according to the JIRA Service Desk documentation, for the autofill to work, you have to allow customers to share their requests:

"Before you begin, make sure your Customer permissions > Who can customers share request with? setting is on Any customer or organization, by searching in this project. This ensures that customers can search for approvers."

https://confluence.atlassian.com/servicedeskcloud/setting-up-approvals-816880004.html

In some environments, this is fine, but in ours, we really don't want customers sharing requests, since the requests have the potential of containing (somewhat) sensitive data.  Nonetheless, we would still like the User Picker field to still autofill.

Could we get request-sharing permissions and User Picker autofill permissions separated so that they do not affect one another?