I didn't go through each vulnerability, but I'd bet that the Heroku security team did as at least some of the vulns don't really seem to apply to Heroku.
Case in point: you for sure are not running MySQL on a Heroku dyno.
You've got a point there, but I'd ask why not remove the packages that aren't being used? Here's some of the raw data about which system libraries are lagging in security patches:
Case in point: you for sure are not running MySQL on a Heroku dyno.