The less atmosphere between you and the sun, the more radiation you'll experience. There was definitely less atmosphere between the remains and the sun in this case than if they were shipped by plane, making the radiation higher.

And if they were shipped somewhere by plane during normal transport by academics, they would have taken the appropriate steps to ensure the preservation of the sample.

I can't say I really understand why some people seem so surprised that the scientists would be unhappy at this, or feel like they scientists are being unreasonable here. Their whole job is to learn as much as they can from what samples we can recover from the past for the benefit of humanity's understanding, and a priceless sample was needlessly handled in a way that may make it useless to their studies, because a billionaire though it would be entertaining to shoot it into space for no real reason...

In what world would they not be unhappy with this situation?

It was dumb to risk something this rare for no reward. That's a problem.

But even with the remains safe, this is part of a troubling trend from the archeologist in question of seeking publicity and raising the stature of the H. naledi finds (which are legit amazing) beyond what he's scientifically proven. Don't blast them into space for a few minutes - show experts the proof for all those claims you continue to make despite failing peer review.

Radioactivity in space alters the remains significantly.

The issue is that you can't guarantee there won't be harm, and by doing it and not stopping it in the future, you are inviting others to do similar stuff. And probably to one up each other.

And eventually there will be an accident and something important will be lost forever.

Y'all are really out here acting like "no harm no foul" like you'd be fine with your toddler running into the street because "nothing happened!" This time. Next time, a semi could be speeding by.