I can definitively agree on the explanation stated infering the second point. However, it is an aspect which needs further clarification, like op said: “someone else’s skin” is usualy interpreted as human directed (https://dictionary.cambridge.org/dictionary/english/someone). This essentially introduces double meaning within the argument.

In terms of vegetable tanning your best knowledge is correct, it costs more as it requires substantially more time thats why it is only used for higher end or artisan leather. Additionally, I have stated synthetic tanning which is comparable to vegetable, but not as bad as chromium.

& the original person’s comment about chromium-salts looks spot-on, & was ignored by your counter.

In regards to that, can you provide relevant information which details it?