At first I was like "Student murdered in watch robbery attempt near Harrods... I don't get it".
Then I read down and I was like "haha arseboon".
It's funny because it sounds like "our spoon".
(Agent Pr1ck llǝɯs ǝɥʇ sʇI ˙ǝɔɐld sᴉɥʇ ǝʇɐɥ l, Wed 21 Jul 2021, 10:45, archived)

no mate it's funny because it contains a funny word meaning the buttocks and anus!

(Smegg Wallace The O.G. Q.R., Wed 21 Jul 2021, 10:50, archived)

well actually I think you'll find it's funnier than that.
Whilst you correctly identify that 'arse' can refer to the peri-anal region the word 'boon' can mean either 'a thing that is helpful or beneficial' or 'a favour or request'
So his name could literally be translated as 'anal favour'!
(Agent Pr1ck llǝɯs ǝɥʇ sʇI ˙ǝɔɐld sᴉɥʇ ǝʇɐɥ l, Wed 21 Jul 2021, 11:01, archived)

it's also a contraction of 'baboon', and used as a racial epithet.
So his name means 'racist peri-anal region'!
(Smegg Wallace The O.G. Q.R., Wed 21 Jul 2021, 11:04, archived)