Just like to share my experience with Nintex Forms rules and comparison of the 'Current User' common context data against person columns.
What I was trying to do was to hide an 'acknowledgement' button (just a standard button which is connected to a field to record a value on the form submit.
The form I have a leave request form and there is a person column called 'Requested For'.
After the form is lodged it sent to their manager for acknowledgement. (This is not a workflow task just a list form item)
The Acknowledgement button needs to be hidden from the user who it is requested for.
I tried to create a rule of current user==Requested For (from item properties)
However this did not work.
What happens is that the current user return the claims windows username identity.
Whereas the Item Properties person column returns the Display name of the user.
I next tried a hidden calculated value control to do a user profile lookup of the current user and return their display name (PreferredName)
However this did not work well.
Finally doing a comparison of the 'Current User' against the named control person-RequestFor worked.
I was able to confirm the value of the person control by adding a calculated value control on the form where the function = named control person-RequestFor
From that I was confirm that both calculated controls returned the claims windows username identity.
Hopefully this helps some others out there enjoying the fun of person columns.