Might work. What is the advantage, no re-pot?
The husk of a young coconut may break down fairly quickly, but if it does not, the process may rob nutrients from the soil. This is the case with fresh wood chips. Not sure about "young" coconuts?
Strange angle. Wonder what @ReikoX would think. He is the wiki-canna-pedia guy around these parts.
Coconut trees might think it is a good idea...