Deliberative process is just one type of exemption and is entirely separate from the national security exemption.
"This category was added after witnesses testified that geological maps based on explorations by private oil companies were not covered by “trade secrets” provisions of present laws. Details of oil and gas findings must be filed with Federal agencies by companies which want to lease Government-owned land. Current regulations of the Bureau of Land Management prohibit disclosure of these details only if the disclosure “would be prejudicial to the Government” (43 CFR, pt. 2). Witnesses contended that disclosure of seismic reports and other exploratory findings of oil companies would give speculators an unfair advantage over the companies which spent millions of dollars in exploration."