Yep. Add to that, the highest post so far she had was a state senator. Would be totally unprofessional to choose someone as inexperienced as her (especially considering Sanders age, and consequently the possibility of having a newbie as president if he has to resign cause of health problems).
Dunno who can be a good VP pick at this stage. Gabbard could have been if she didn’t burn herself in latest months. Harris might still be (acceptable for moderates, ticks the age/gender/race check), Abrams too but then she lost her only important election, same for O’Rourke. If he goes for some bizarre choice, then he will alienate anyone bar ‘Bernie or bust’ crow, and they already are converted, so no point preaching to them.