This may be a controversial post because it strays from the exploitation of non-human animals, but this is a story about human bodies being sold and used without their prior consent, which to me speaks to a similar (albeit more severe) indignity that non-human animals face in the medical industry. That is to say “this isn’t vegan”. Feel free to downvote this post heavily and say as much in the comments if you feel this isn’t on-topic for this community, as I know there are plenty of other places that will address this with an appropriate level of appallment.
I’d argue it’s vegan to use animal products if and only if the animal has died through no means of your own and you are not indirectly causing more exploitation.
Second hand leather is not vegan because you indirectly support the leather industry by fueling demand for leather. Someone may be more inclined to purchase something made of leather if they know they can resell it at a later date (like a leather sofa).
However, I’d argue eating roadkill you accidentally killed yourself would qualify as vegan since there are no moral issues with that - consuming it doesn’t fuel the demand for animal exploitation. Additionally, it causes you to consume less food produced through industrial agriculture (which is not sustainable in its current form), making kt better for the environment.
For me, exploitation := intentionally harming an animal as a means to an end
your personal definition is not widely used enough to make it into a lexicon.