If this is allowed to stand OSHA can mandate anything. Congress can change it, but will they?
One of the things I talked about when this first hit was that OSHA, the EPA, FDA, etc. exist outside of the legal framework.
They pass regulations without a law. Enforce it, and do everything without much recourse to elected officials.
Congress as currently constituted wouldn't touch it. In fact, this case could give Feds much more power, in which Congress will be overjoyed.