While all true, using a couple week stretch of ABs from last season, prior to the offseason adjustments Hiura made to his swing/approach in large part to try and get his K rate dropped, is not a good reason why Hiura has had 0 MLB at bats this year for this year's roster. Hiura was very good in August 2022, also very good in limited July action and in May...but that didn't stop the team from sending him down to Nashville multiple times during the 1st half of the 2022 season. The low 0.500's OPS he put up over 20 September games is a bad stretch of offense, no doubt (42% K rate over that time, not the 50% you mentioned, btw) - but many players go through extended bad stretches similar or worse than that at the plate while teams patiently wait for the hot streaks to come back that can carry them offensively.
My problem with Hiura's usage the last 2+ seasons has always been that at the first weeklong or moderately extended stretch of struggles, he would get optioned back down to the minors - and even when he was hitting well enough to continue getting sporadic at bats in Milwaukee there were times he'd get optioned due to maintaining roster flexibility and/or not giving him an everyday spot in the lineup as the team's DH once it was implemented in the NL. Slumping with a high k rate sticks out alot more than putting the ball in play weakly 90% of your ABs when you do make contact, but the end results actually look very similar in terms of offensive production.