There should be an outright ban until they can prove a safety case. There are too many involved in these activities who think they're above any regulation and think they know best.
The same thinking seems to have been involved here. This incident happened in May when every safety procedure in the book was totally ignored by the idiots running this train. Instead of stopping, they decided to carry on and were heading into the path of an HST travelling at more than 100 mph. Had this happened, it would have been the biggest loss of life in the UK. It was mainly hushed up and only reported in the railway press because it involved "steam enthusiasts" on a day out.
http://www.bbc.com/news/business-32622534