The Comelec does not want to give any reason why it does not want to release the list of qualified party list nominees.

When asked the reason why Comelec does not want to release the list of the 93 party-list nominees, an official in the comelec law department simply answered: ““Basta ayaw lang”.

For others:

“There is no rule or reason for the Comelec to keep it a secret except to protect the fake party-lists from open condemnation and public pressure. The lists of nominees are public documents and its public scrutiny flows from the logic of the Supreme Court landmark decision on the party-list system.” (Partido ng Mangggawa)

source: Inquirer March 30
Inquirer March 31