I was surprised that the blessed Margaret seemed to be taken in by him, she wasn't easily fooled.
It had to be absolute desperation. The Northern Ireland Secretaries for the period (Roy Mason, Humphrey Atkins and Jim Prior) weren't idiots. But none had any knowledge of the car industry or selling expensive goods in the USA or anything which might contribute to the DMC project. It appears that they were also unable to read newspapers.
We can all be wise after the fact. The thing about DeLorean and the DMC project is that almost every prediction was true but a little bit worse than anyone suggested in print or on telly.