Having a rescue plan is a difficult thing with suspension. If you think about the reality, I can't think of many instances at all when you can get to them in 10 minutes.
I find it interesting how there are many opinions on this. How many have had formal H&S training of any description? IOSH, NEBOSH, even manual handling, slips, trips and falls and working at height training is essential for window cleaning. Maybe not NEBOSH, but EVERYONE should have done the rest.
Maybe the employer is not being dragged into this episode because he can prove he had done all he could to train his staff, but if they disregard it, it's not his fault.
Is clink the right option? I don't think so. That affects your family, future employment, insurances etc. If he was my employee, who I'd had for a period of time, I knew was a good worker and it was his first offence, he'd be in for a disciplinary and given a final written warning. If I'd spoken to him about his lack of H&S practice in the past, he'd be dismissed for gross misconduct, without notice.
From that, hopefully he'd have learned his lesson and could go on to get a job elsewhere.