Moon Minutes and Star Seconds weren't fixed amounts of time in the veiled realm. The rules of the real world did not apply on the other side.
A moon minute was the duration for which the moon was visible before it disappeared behind the clouds, and a star second was the time which it took for a star's twinkling light to be visible to those on the ground. Both these were variable units that could stretch as long as an hour or less than a second.
All Xander knew was that there wasn't enough time to calmly negotiate with the parasite. If the child was killed, the conscious half of the Host Soul would merge with the parasitic soul fragment, and Noah would gain complete control over all memories in this plane and be able to acquire the human body he had been yearning for.
