I know what it was saying: it was just weird & poorly explained.

A good analogy should compare subjects

• with similarities relevant to the conclusion
• lacking relevant dissimilarities that weaken the conclusion's likelihood

and it should hold up with other subjects featuring the same relevant similarities & lacking the same relevant dissimilarities in satisfying the conclusion.

That milking cows necessarily leads to suffering isn't obvious, needs to be explained. The analogy comparing milking to rape seems to break down for those aware that dairy cows are bred to overproduce milk, so they need milking (or a very hungry calf) to prevent pain & mastitis. Rape seems quite dissimilar in that respect: no amount of it is necessary to ease pain or prevent infection. It's harder to conclude that something thought to be needed qualifies as suffering.

Therefore, a clearer argument (that was provided elsewhere) is needed.

There's also the matter that the comment they were responding to wasn't arguing about morality, since it wasn't clear the top comment was stating a moral position, either. The top comment merely referred to milk as "crazy" (due to lactose intolerance) & "stealing from cows", which come across as hyperbole for unnecessary when the cows presumably don't care & lack any concept of property rights. That's where unexpected moralization with rape analogy raised the charm of lemmy as

calm, open-minded, delightfully reasonable

to new, exciting heights.