I’m not sure that there needs to be a any grand cosmic reason for life to exist. Life could just be an accident of random events in our little corner of the universe.
Natural selection offers an explanation for how life changes across generations in response to challenges in the environment. It does not require a plan, just that the outcome of a chaotic process (reproduction) creates mutations that produce a slight edge, or at least no reduction in reproductive efficiency.
It is just a public statement of support. There are only consequences to the extent that people care about/respect the opinion and judgment of the person giving the endorsement.
In this case, it’s valuable to RFK Jr in so far as individuals listening to Joe Rogan either think Joe has good insights into who should be president, or just want to be like him and will vote the way they think he will vote