Denti It is deemed safer to take it into the air then abort an take off where a crew member who has to do critical tasks is incapacitated. After all the aircraft is most probably still working fine and modern aircraft can be flown quite comfortably single hand once you get your head around the fact that one of the two up front just croaked.
True,a reject after a second call out at 'low speeds' is expected.
A reject close to v1 on a limited runway is a risk assessment the pilot need to be ready for.I would continue in that case..
The only hope then is that there is a medic onboard...