I'm certain there will be investigations from the government, not only due to the suspicion of a foreign state attack but also on the grounds of Starlink not sufficiently securing their premises.

It's not the responsibility of security agencies to prevent two guys from entering the premises of a critical infrastructure provider with gasoline.

They may have prior intelligence to act on this, but it is the operator of that facility who has the responsibility to ensure a certain level of security and resilience of his own premises, and this is strictly defined.

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> "Are Oil tankers and Cargo ships supposed to have air defense?"

No, this would turn a civilian into a combatant ship, causing it to lose the civilian protections of the UN (The Ocean is governed by conventions of the United Nations, it's a different jurisdiction)

And still, oil tankers and cargo ships have requirements to secure themselves against piracy, terrorism and even warfare, mandated by the international maritime organization.