They didn't stole the boat, they seized it. Not wanting to sign an erroneous legal document is respectable, calling the DHS stealers is clearly not. Don't be surprize if they won't cooperate to solve the matter ASAP.
Are you a repo person and my car loan invalidated? Did I steal my car from someone else? Was a car matching my car's description involved in a crime nearby that a judge ordered a warrant for a black ford F150 with a "geeks rule" bumper sticker? Are you a Customs/Border Patrol Agent and I do not have the proper paper work on the car I'm attempting to drive in? Are you a police officer and I do not have a driver's license on I-75? If any of the above, lawful seizure by government authorities, not theft.
DHS behaved in a morally indefensible manner. I don't care if Arrington is telling a one-sided story and was actually a total asshole: DHS works for the American public and my tax dollars pay for the pain of putting up with jerks for the public good.
Hence, they stole his boat. If the President were to show up at my parents' doorstep without a warrant or probable cause and shoot my little sister because he was having a bad day, would you call it a lawful execution? No, it's murder.
That's an extreme exaggeration to prove my point. But that's where your logic ends up. Having a badge that reads "Government Agent" does not mean all your actions are moral or legal.
They confiscated his boat because the papers weren't in correct order--and the official, according to Arrington's story, was willing enough to let it go if he wouldn't be an officious prick about it.
He will get his boat back once the paperwork is completed correctly. Shocking, I know, but he will.