Lots of talk about lack of SA, but... SA depends on your perception.
If you haven't picked up the error, your perception is that you have the correct information and your SA is based on that.
Yes, we'd like to think we'd all have picked up the incorrect read back or the opposite traffic clearance. But, no one here was there to know what was happening, what other threats were there.
Oh, to be as perfect as some here!