I would do nothing and it wouldn't bother me in the slightest. Hair is only anathema to me if it's
d i r t y. (however . . Himself would look beyond ridiculous with that particular style! Bahahaha!) When I was a kid that style would have indicated a Teddy Boy or a Spiv. We also had Mods and Rockers. Jeez, I'm old.
Well, after I recovered from my jaw dropping to the ground, and stopped laughing after about a week, I would march him right back to the hairdressers , and ask him if he had been temporarily insane !!!!