To control administrative access, Linux keeps a list of all the registered users on a machine, in a group typically known as “wheel,” who can be granted full root access (usually through the Unix sudo command).
A knowing attacker could get full root access by modifying the wheel group, either directly or by manipulating an adjoining program such as the Polkit graphical interface for setting user permissions, Alert Logic said.
This is patently stupid. Yes, if you give a badguy administrative access, bad things can happen--even if you use a fancy GUI to give the bad guy administrative access. The only thing that is even slightly newsworthy here is that maybe a novice admin won't understand the purpose of the wheel group and could be tricked into giving permissions, but there are a lot of ways you can trick a dumb admin, there's no need to single this one out.
If we look at jet aircraft, wear depends on the airframe and the engines, and the airframe seems to be the number of pressurize/depressurize cycles as well as the running hours. Engines get swapped out routinely but when the airframe has enough stress it's time to retire the aircraft lest it suffer catastrophic failure. Rockets are different in scale (much greater stresses) but we can expect the failure points due to age to be those two, with the addition of one main rocket-specific failure point: cryogenic tanks.
How long each will be reliable can be established using ground-based environmental testing. Nobody has the numbers for Falcon 9R yet.
Weight vs. reusable life will become a design decision in rocket design.