Why did Kenny Omega dress up as a member of the Shinsengumi?

The Shinsengumi were a highly controversial militia group that operated in Japan during the late Edo period. They engaged in abusive behavior, and some members continued to carry out violent actions even after the surrender of the shogunate. They were responsible for assassinations and attacks on political opponents, and they killed more of their own members through internal purges than they did in fighting against Imperial loyalists.

I wonder if Omega was trying to signify something here or just cosplaying.