If the older dev is compensated more/has a higher level position, they are expected to provide more to the employer/product, whether it is through their excess wisdom or knowledge or responsibilities or otherwise.

They shouldn't be expected to compensate for their lack of youth in any way, as youth isn't a metric that has any relevance to their work in software development. And if they are of the same title/total comp as the young dev, there is nothing wrong with them being on par in terms of skills/knowledge/responsibilities.