Old folks are fragile and the more time we spend sitting on our rear ends, the more fragile we get.
The last time I looked, the risk of death per hour of cycling was nearly identical to the risk per hour of driving. Ditto for serious injuries. Is the BIL going to stop driving? The only studies I've seen on the benefits versus risks of cycling all say that cyclists live longer on average. However, the ones who died prematurely might feel poorly-served by such studies.