It was clearly a response to the grandparent's "... isn't like this for other animals". It's a fine thing to aspire to be better, but we just shouldn't be claiming that human behavior is any way less natural than that of all other animals.

You can also consider the subject in terms of IT. Firewalls can be argued to delimit territory, as can login systems. Sandboxes are probably the reverse, in terms of keeping something in instead of keeping it out.

Some cells have cell walls, and viruses as I understand it have to penetrate that wall.

Nuts and fruit sometimes have protective shells.

An argument could be made that borders and territory are fundamental.

For an agent that seeks to defeat border control mechanisms, it can potentially be effective to convince the target parties that border control mechanisms generally or specifically are harmful, are useless, or have drawbacks. This is not always completely false in all cases, for instance regarding immune systems misidentifying harmless allergens as harmful, causing potentially significant harm as allergy. However, if an agent uses such approaches, they have to be careful not to buy into that idea themselves, lest matters may become strange and weird. And, in the modern day, if an agent is especially successful and competent with defeating border control mechanisms, considering the extreme power that the human species holds these days, such as with nuclear weapons, it puts an extreme responsibility on such successful agents, at least in the current systems. Otherwise, the consequences might be extremely detrimental to the human species as a whole.

We are animals, we shouldn't try to avoid that as if its a bad thing.