because I feel that is much easier and simpler and quicker to let the NEXT person in line do it, first off when you pardon prior to conviction you are admitting guilt in absence of a trial
so if Obama pardons her or she does herself she has admitted to the crimes and exonerated herself, second she cant pardon herself for every crime she has or will commit.
its pretty precise that it has to be in the context of doing ones duties as president, so if she admits guilt via a pardon she will be open to OTHER prosecution on future charges...
if she waits for conviction and then lets the current sitting president do it, off the hook
so if she wins, she will not do it, she will hold on as long as possible and then resign, via nixon, and let tim kaine do it
just my take
