It's because the port is a forward operating base and entrenches the annexation of Northern Gaza. They built a road splitting Gaza into two and are shooting anyone who approaches it. Add to that the US wants warships present to defend the oilfields it's just been liscenced by the occupation forces.
This is, and always was, about money and ethnic cleansing. Fuck israel, free Palestine.
The attack was claimed by ISIS-K - a foreign fighter offshoot/offbrand. Funny thing is that ISIS-K fighters were getting lifts from American chanook helicopters in Afghanistan and is largely made up of US assets and/or people formerly trained by the US in Afghanistan.
Lots points to it being a CIA asset, tldr. They're a dirty army that can be used to keep an area distabilised or prevent other geopolitical powers from building infrastructure/influence (the nutshell purpose of ISIS-K, particularly in Afghanistan to prevent pipelines being built).
They had the inside scoop on an attack outside any usual operating theatre by a group with tangible links to US cooperation/orientation? No kidding.