Incorrect I'm afraid. Like I said, I remember when what we call now the NIRMS and NI Green lane were called "trusted trader scheme" & "orange channel" as UK policy proposals into the withdrawal agreement negotiations.
They were produced by the NI group. Obviously the UK would like them to have been the basis for GB/EU, but May also didn't want the result she got: hard border or stay in. They knew that was unlikely to fly domestically. A lot of work went in to looking at specifically the NI issue.