Anyone popping in out of nowhere (in Atlantis) would be assumed to be hostile. A lot of gun pointing and distance would be maintained until they ascertained her intent.
I doubt that Buffy would make the mental jump to Atlantis (as in the lost city), she would probably make some quip about a cheesy nightclub or the deep south.
Intriguing beginning. I must admit I am having trouble imagining a retired SG1 sitting back and letting Shepard do things his way, but I really want to see you make it happen.