Odk central as admin if i make project viewer account

If I make a Project viewer account they only download data (perfect)
but the problem is also seen in my form version and download as xls form .
I want hide the (form version Tab) in Project Viewer Account because for security point of view

Why is downloading the form a security issue? What sensitive data do you have in the form that a project viewer (who can see all the data across your project) can't see?