These sorts of analyses get complicated fast. Walking is riskier in part because you're more exposed to the "killer self-driving cars", but also people with preconditions will walk. Like, if you're drunk you'll walk home, if you're unfit you're more likely to walk than cycle, etc., people walking probably get mugged more often, ...
But OP is making the opposite assumption here - that cycling is riskier. Which, keeping all other factors constant, seems intuitively correct to me since you go at a higher speed and you are on the road with cars rather than on the sidewalk.
