The fine was issued by the state of Indiana. That's stated in the article and you can confirm by looking up further sources.

OSHA is federal and under the US Dept of Labor.

The state-level IOSHA is a part of the Indiana Dept of Labor.

I have no idea why the article keeps mentioning OSHA. It clearly is not to show the disparity between state and federal enforcement. Maybe just to confuse comments on HN . . .