Well, as long as they exist in a different "coordinate system" (a dimension or realm where our physical laws don't apply), our scientists wouldn't "have a problem" with their existence; from our scientists point of view, the question of their existence or non-existence would not be falsifiable (i.e., no conceivable test or experiment could "reveal" them to us).
But as soon as they (the "angels") entered our "realm" or "dimension," then they would be subject to the physical laws of our Universe.
Regards,
And there is first-hand testimony that they have done that, enter our coordinate system. They use vehicles from their coordinate system in our coordinate system in order to fly around.