There's no other explanation. There could be 100's of valid reasons that a JDA member couldn't be reached. One member visiting a sick mother could be 100's of miles out of reach.
This is Africa, not New York City! If you get far off the beaten path you might as well be on the moon!
Anyway, my point is that I believe both Gandur and Mark's source are right and presented one (now two) of many scenarios offering explanation.
The point is the rig is sign, the JDA knows about it, and Gandur, for whatever reason, hasn't gotten the approval.