On this technicality I disagree, in that the Peelian Principles necessitate a public that acknowledges the legitimacy of the model of governANCE to which the public has delegated the power to use force.
Currently, within the Westphalian construct of "sovereign nations" (in which the national governMENT is the model), there is an inherent rejection of one nation's authority to impose by force its citizens' will upon the people of another sovereign nation.
So ... the "community" to which it is incumbent upon the citizens have an interest is THEIR community, not the "community" that represents another sovereign nation.
However, our conclusion on the security posture of an independent (sovereign) seastead is, I think, identical.
If each "sovereign nation" represents its citizens ... and the "matters of defense" are consequently "incumbent upon every citizen in the interests of the community" ... then those citizens will logically have a tendency to interpret "defense" to include the potential of "pre-emptive strikes" when an attack appears imminent (clearly a subjective determination).
That is the current global norm, and that won't disappear without a superior model for guaranteeing "the interests of the community" to the citizens of all parties concerned (i.e., to the citizens of all nations involved).
Without such a superior guarantee, sovereign nations would be negligent in securing "the interests of the community", and the citizens would replace the negligent politicians with others who are more hawkish on "matters of defense".
The end result is independent military and paramilitary forces, each representing their unique "community" (both nation and rebellious factions that exist) with unique interpretations of what is "best" for their own citizens.
To presume the sufficiency, in such an environment, of a mere proclamation that a seastead is "peaceful" and "non-combative" would be idiotic.
If such proclamations WERE sufficient, then military invasion and terrorism wouldn't be a threat ...
... and those arguing for an abandonment of defense would be building floating concrete seasteads in the Persian Gulf.