What if there's no email address?

I'm using the Optional mail on register → module which means that user accounts don't need an email address. That in turn means that users without an email address cannot make fields private (ticking the 'private' checkbox and saving their account doesn't do anything - the private field in unchecked when the form reloads.

This would also be an issue for sites using modules that allow multiple user accounts to have the same email address I imagine...