He is not amused.
I got this crazy idea when I watched that episode where they were doing photoshoots in swim wear or something... Anyway, Barnaby was amused, Tiger was not...
Then it hit me...
This is a photoshoot where they dressed up as each others' persona-thing... Wild Tiger as a cute bunny!
Reporter: Mr Collateral Damage, what do you think of your outfit?
Kotetsu: Huh? Collateral Damage, Hey!
Please don't kill me, Kotetsu.
I can actually imagine Barnaby in the background trying to suppress laughter.