It's a given that LIGO will release it's data in due time. A more proper question would be "When should LIGO release its data?" Possible choices would be 1) Now; 2) After some reasonable period of exclusive access; or 3) Never.
The second choice should have the most responses.
LIGO is funded by tax payers, so they are required to open their data eventually. They have an open data policy, which releases a selected bit of data around all published events. After the first few events have been published, all data will eventually be published. The reason not to do that immediately is so that the LIGO has enough time to vet their data, and to be able to write up an articles. They have worked for 40 years to achieve these amazing results, so understandably they would not want to be skooped by an outsider for any results hidden in their data. But after they had a first look, everyone will be able to eventually. Nothing sinister going on ...
LIGO open data website:
Those who hide data have something to hide. Fraud, misconduct, etc.? Be suspicious
Black boxes - or even "grey boxes" - are contrary to the spirit of science.