This might defuse an existence proof, but any real technology transfer
could undermine the economy by obsoleting major industries. Their
owners are almost certainly going to try to encourage legislation to
prevent this happening.
It could even cause the destruction of the current work for money concepts
and produce something more like the economic model hinted at as that
of the earth in the Star Trek Voyager era in that TV show (money is
a way of sharing resources and avoiding direct barter, so I'm not convinced
this would ever work).
Having 1000 year old prior art suddenly revealed might have interesting
effects on the patent system.
An ETI might well be reluctant to reveal their science and engineering
knowledge for such reasons.
It's also possible that the ETI's have been successfully running a
centrally planned economy for millenia, undermining one major US
There are a lot of things about western grass roots politics which could
conflict because they conflict with current prejudices.