Not even sure why you want to do that. Even if the control is set to "edit mode" when the entire form is in display mode there wont be any save button to make those changes, further are you actually trying to create save button as well in View mode? Why would you do that though?
Believe you could pass the edit form URL to your managers rather than the view mode? As view mode is designed from SharePoint's perspective for only view and If Nintex does manage to provide you controls that is editable during View mode, I still believe you would be better on designing a solution where you only use edit mode to save changes.
A reason i want to be able to submit on view mode is to re-open something.
Right now i have a form with 100 fields on it, i'm using View and edit mode based on statuses. If the status is Complete, they access it via View mode so that i don't need to rebuild the form with edit and display mode fields (since i can't set that based on expression).
One of the fields we have on the form is an attachment field, while in "compelted" state we do not want the user to be able to upload/delete new items. But since i cannot set the display mode for this type of field, we MUST use the View/Edit forms.
I want a single tickbox to be "Re-open" and if the user then clicks submit on a button, to save that so that workflow can then execute to "re-open" the items.