Theoretically, probably not a great experience for the people some 300mi away or closer but I don’t think it would be an extinction level event. Speed is how most of the energy gets transferred. Lower speed, smaller boom.

I think it has to stay theoretical though. You would have to turn gravity off though or make the asteroid such a weird shape that air resistance slows it down to that speed before it hits. And I think it would have to be sail-like at that point hitting at the right angle, making its impact much less threatening and making it way more likely it would’ve burned away in our atmosphere anyway. Before it hits earth there will be gravity pulling on it, most effectively from the sun and then earth. So even if cosmic forces got it to reverse beep beep beep speed before it enters earth’s gravity well, which I would call unlikely with an asterisk, then it would speed up 9.8 m/s or 22 mi/h every second it falls from the heavens. Thus making the impact more impactful than reversing speed. The asterisk being that there is a much bigger other new body in space that exerts enough gravity on the asteroid to slow it down. Which means it’s close enough to mess earth up in other ways (tidal waves, megaquakes, etc.) even if it does not also hit us, which I would assume it does though if it got this close already. So then we’re back in extinction territory whether Corsica hits us or not.