Members of Parliament enjoy immense privilege to speak openly in the context of their Parliamentary duties. Any MP, entrusted with classified information, would be able to disclose same in Parliametary business without fear of prosecution under FISOIA. They would likely lose subsequent access, but the concept of a FISOIA ‘gag’ on utterances made in the course of parliamentary duties simply isn’t true.
*There’s currently a very narrow carve out to that for members of the National Security and Intelligence Committee of Parliamentarians who receive classified information in the course of their NSICOP duties. There’s a Supreme Court decision pending imminently on how that squares with Parliamentary privilege.