In colourbrids there is a good deal of variation in venom and venom delivery. Most of the rear fanged colourbrids, such as the False Cobra have to chew hard and long to inject venom. Nigel may not have been envenomated as when you look closely the rear end of the jaw is not chewing on his hand. Whatever the case I think he thought it was non venomous.
Extract from Journal: Toxicon, Vol. 26, No. 6, pp. 323-524, 1988
While attempting to photograph its unusual, cobra-like defensive posture, the author
was recently bitten on the right thumb by an adult (760 mm)M. moilensis. Not wishing to
hurt it, the snake was allowed to bite deeply for about 5 min, at which time it disengaged
voluntarily. Several puncture wounds were observed, two of them, probably caused by the
fangs, slightly larger than the rest. Local edema, followed by numbness, manifested
themselves within 15 min. No treatment was given. Edemaand numbness were limited to
the thumb itself, and were felt for nearly 24 hr. No other effects were felt.