I agree it would be a hassle to have someone come in and drive the car while you're away. But apparently this would be needed, as the manual says (on p. H10): "If you park the vehicle for a long time, the hybrid system will discharge. You need to drive the vehicle several times per month to maintain a charge." I think "several times" is a bit vague -- once per week? Mine sometimes sits for 5-7 days without being driven, and it starts right up, no problem, so I'm not sure what "several times per month" translates to.
It's also worth noting that even gasoline can go bad after a few months, so the Niro may not be unusual in needing "babysitting."
2017 Niro EX, Black w/Gray Interior, Adv Tech/Sunroof