Pardon me if I am being obtuse, but the point of the original comment was "black holes do not exist in our universe, since time dilation at the event horizon is

Pardon me if I am being obtuse, but the point of the original comment was "black holes do not exist in our universe, since time dilation at the event horizon is infinite", yes? This is what I am arguing against. The event horizon is within the future null infinity of your observer; i.e. the observer may choose to travel towards to black hole, and will asymptotically fall into it and thus undeniably observe it. Hence it does actually exist even for this observer. Moreover, the observer can observe the shadow, effect on nearby masses and the gravitational lensing produced by the black hole, thus indirectly observing the black hole, even though he cannot see the actual event horizon.