Pitching injuries spiked dramatically league-wide in 2021 because of the short season in 2020, even after teams limited pitch counts in 2021. It even carried over to 2022 and a bit in 2023. They need to be careful here, Horton only threw 34 IP last year.
You're right, at this pace there's just no way he's pitching in the post-season. But he could also get hurt at any time and miss a couple of months so it may not be an issue.