Seems bunk to me. First, the tidal effect will be greatest at new moon, when the moon and sun tidal effects are in the same direction. 2nd, how close does the full moon need to be to the explosion to be considered to be "coinciding"? I would assume that they mean on the same calendar day. That gives a ~3.5% chance that an explosion would coincide with any particular phase of the moon. Having 3 out of 50 (6%) isn't so far from 3.5% for me to think that this isn't just random chance.

Especially if they relaxed their standards. Suppose they considered an explosion to coincide with a full moon if one occurred within 24 hours of the other. Then you'd expect such a (random) coincidence ~ 7% of the time.