In Jainism, a Tirthankar is not a stone. A Tirthankar is a jiva with a body, and while in worldly life they may walk, speak, and act — but their inner state is completely detached and free from passion.

Important points:

1. As long as there is a body, some harm is unavoidable

In worldly existence, even breathing, walking, or moving can involve subtle violence to one-sensed beings and other life forms. Jain dharma accepts that absolute non-violence is fully possible only after liberation.

1. Tirthankars acted without attachment or selfish intent

Their movements were not done with greed, anger, or negligence. They acted only according to the remaining body-karma and for the welfare of souls.

1. Their violence is not like ordinary violence

Ordinary himsā comes with kasāya: anger, pride, deceit, greed, or carelessness. A Tirthankar, being spiritually pure, does not bind karma in the same way.

1. They did not “choose violence” for worldly reasons

Their walking, speaking, teaching, and moving were part of the embodied life until kevalgnān and final liberation. They were not trying to harm beings.

So the correct Jain understanding is:

• A liberated soul is beyond all activity.
• A Tirthankar in worldly embodiment still has to live in a body.
• Minimal unavoidable harm can occur in embodied life, but karmic bondage depends on intention, attachment, and passion.

So no — Jainism does not say a Tirthankar should “just sit like a stone.” Rather, Jainism teaches that while embodied, even the greatest soul may have unavoidable bodily activity, but remains inwardly detached and spotless.

If you want, I can also explain this according to Digambar and Shwetambar viewpoints.