[generuso]

One of their patents describes exactly that -- driving a hardened stud into the softer metal of the deck, essentially by using a gunpowder actuated nail gun:

https://patents.google.com/patent/US20240092508A1/en

They have also included a way to disconnect the stud from the leg afterwards, such that the deck can be tidied up conveniently after the rocket had been removed. This is a neat idea -- the damage to the deck should very localized, and the rocket gets secured quickly and without putting human welders at risk.