Yes, at or near 35%. 35% isn't near 30%. If you told me he would K at 30%, then I would say bring him up because he can have some success with that, based on recent history th/o the league. But Hiura K'd 42% of the time last year...
K% isn't "arbitrary". It's correlated with production. Long at-bats which end in a K are useless because there's a 0% chance of getting on base, plating a run etc.. So, the more K's you rack up, the less your production will be.
Joey Gallo is the only player w/ K rates consistently as high as Hiura who has been able to establish themselves in the big leagues. And even then, Gallo is one of the most maddeningly inconsistent players in the game. Not to mention he has a leg up on Hiura in 3 major ways; specifically, his BB%, his defense, and his EV/Barrel%.