Allowing one damaging thing isn't a good enough reason for allowing another damaging thing. In both cases the costs and benefits need to stand on their own merits.
Actually, no, I don't agree with that. It's more of a balancing act than a piecemeal analysis. Being generally frugal leaves you more space to waste a few resources on specific things. Now, some things are over the limit regardless of how frugal you are generally, and pet cats may or may not be one of those.
It seems like here you’re arguing that banning some damaging things might make some others allowable. That’s the inverse of the argument I was discussing.
I understand the argument and it’s reasonable, but in the case if each activity under consideration, they have to be assessed relative to the total harm to the environment, not to directly against each other individually. But there could be a hierarchy of comparison.
Still, as I said this is the inverse case to the one I was replying to, which I still think is completely unreasonable.