Sufficient evidence for conviction of corporation, as the relevant regulation requires that the workers "shall be protected" by the safety device, so mere provision of the device, followed by the supervisor's observation that it wasn't being used sufficed; the fall was a foreseeable and natural result.
Evidence of other safety omissions was properly admitted, as it helped to establish a knowing violation of the rules.
Sentence was procedurally correct, as there was no need to mechanically recite all of the factors, and a fine beyond the apparent means of the corporation might legitimately have been aimed at revealing any hidden funds.
http://media.ca8.uscourts.gov/opndir/18/07/173148P.pdf
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.