How did Shed's skull and brain matter not explode outwards at hypersonic speeds, killing everyone in the room when he was head-shotted by a railgun slug?

According to Spacedock on YouTube, the railgun range is about 1,000-10,000 kilometers. I timed the clip from the show where the Donnager fires the first railgun slug and it's about 0.8 seconds between the time it launches and the time it impacts the protogen ship. Maybe it's just sped up for theatrical effect, but I don't think so. So, assuming the ships are 1,000 kilometers from the Donnager, here's my math:

1,000 km / 0.8 s = 1,250 kilometers per second

Light travels at 299,792 kilometers per second: 1,250 km/s / 299,792 km/s = 0.00416955755 km/s =

0.4% the speed of light, and that's at minimum range, that number is probably higher.

So when Shed gets his head blown apart from the unlucky precise railgun slug, how does his skull and brain matter that should now be traveling at hypersonic speeds not kill the people around him?

Obviously, most of his head would instantly be vaporized from the energy transfer, but there would still be a massive shockwave from that. I think Amos and Naomi who were sitting right next to him should definitely have been killed from that. But then we wouldn't have a show, lol.

What do you think?