No, the OP’s argument is assuming that the lives of farmed animals is net negative. It’s saying that farmed animal welfare might at most be neutral, which would mean that, on expectation, farmed animal welfare is harmful. Nevertheless, it would be less harmful than ignoring farmed animal welfare would be, which means farmed animal welfare is still net positive.
Meanwhile, the argument in your link argues that farmed animal welfare may be net negative, but it relies on the opposite assumption that the lives of farmed animals may be net positive.
Sorry if I misunderstood, but does this rest on the assumption that farmed animal welfare is net negative? More on this here: http://interestingthingsiveread.blogspot.com/2018/12/veganism-may-be-net-negative-but-we.html
No, the OP’s argument is assuming that the lives of farmed animals is net negative. It’s saying that farmed animal welfare might at most be neutral, which would mean that, on expectation, farmed animal welfare is harmful. Nevertheless, it would be less harmful than ignoring farmed animal welfare would be, which means farmed animal welfare is still net positive.
Meanwhile, the argument in your link argues that farmed animal welfare may be net negative, but it relies on the opposite assumption that the lives of farmed animals may be net positive.