Locking cells until conditional formatting rules return false

Hello,

I have a workbook that uses this conditional formatting (=OR($A2="",$E2="",$E2="mm/dd/yy")) in a table with ranges A:E.

I have a column F that read: "Read to transfer? y or n?"

Is there a way to not allow a user to type 'y' or 'n' until the conditional formatting is no longer applied to that row?

I have attached the workbook.

Please help!