As a lunar geologist, I really should have liked this story (or three) about the Moon. But I didn't, for all of the reasons people gave.
I did want to clarify one thing from the forum posts, though:
....not to mention, regolith (the material of the moon) is already extremely dark. Covering in ash is likely to *lighten* it. The reason we perceive the moon as at all bright is
a) The sun shines on it and the sun is REALLY BRIGHT
b) We see it when the sun is down, and NOT lighting up our atmosphere, and we see it against a black background with superfaint stars....
Only the mare regolith is very dark, because the maria are made of basalt, a very dark rock. Regolith from the highlands is quite bright, because the highlands are made up of anorthosite, a very bright rock. So, a carbon-based ash would, in fact, darken the highlands. Though, it wouldn't be enough to make the Moon disappear, because even the very dark maria reflect enough sunlight for us to see them.
Also, we do see the Moon when the Sun is "lighting up our atmosphere". It is not uncommon to see the moon during the day, especially in the early morning or late afternoon.