The proposal looks like a solution looking for a problem - there is a problem with dangerous cycling, but I'm far from convinced that it's "deaths by". Currently, it's just a button to press on the culture war panel.
I absolutely agree with the quote above though (and not just for road safety, but probably the whole of the law book, and tax codes, and...); our road safety laws (like everything else) have been developed piecemeal; starting from a time when the only way to go faster than a run, was on horseback. Mostly, of course, it dates back to the 60s when cars were... different beasts.
It's evolved piecemeal, and really wants a cohesive overhaul (which will probably be needed again in 50 years time).