What do we do if SETI is successful?

former chairman of the board of the SETI Institute John Gertz:

'In fact, the author has heard from serious U.S. SETI researchers that they are convinced that “men in black suits” will appear at their laboratory door the moment a detection is confirmed.'

Source: https://arxiv.org/pdf/1701.08422

This seems like romanticizing. I don’t get the impression that maintaining a constant watch on SETI researchers is something any intelligence agency is incentivized to do.

As it sounds like you know, it would be great if you can articulate the boundaries of a prototypical intelligence agency mandate. Because then it should be a cinch to describe why ‘communication from a foreign power of as-yet indeterminate technology advancment relative to modern day superpowers to (checks notes) members of any of the 200 some odd nation-states on the planet who can afford operating a radio telescope’ doesn’t fall within that mandate