100% agree. Also, remember, Achamian was in the process of lying to the Skin-Eaters and leading them all to their eventual death. A groesome and terrible journey that ends with the entire band's death. This this weighed on his soul? I do.
If not that, well, how about all the hundreds and thousands that his Gnosis has burned to cinders? What difference would it make if you murded all those people 1 by 1 with a knife, or all at once in a big fire? To me, not much.
It just so happens that magic in Earwa tends to kill people rather than save them. That doesn't mean that digging a tunnel with the Gnosis would damn you, just that a sorcerer tends to be more likely to be damned because of his acts of atrocity, rather than the simple use of magic itself. It seems far to simple, and doesn't make much sense, to assume that All sorcerers are damned because thats what it says in a book.
Though, we could also talk about objective/subjective reality in Earwa, and say that if everyone believed schoolmen damned, then its possible that they would be. But, if that was the only reason for the damnation, then if the general concencous changed, so too would their fate.
All in all, the JE provides only the most simplistic and simpleminded proof of damnnation. We don't even know if its right, how it works, and who is running the damnnation machine. A sample of one is not proof of anything. It far more likely to be a red h haring provided to us by Bakker to throw us off the scent.
Or at least, thats what I think.