Yes, I see that now. It makes no real sense unless read along with 5 USC 552(c).

I can see a purpose for this, however: if anyone - individual, news organization, whatever - makes a FOIA request for, for example, all records pertaining to a confidential intelligence investigation, it would be better to deny the existence of the investigation rather than to reveal its existence by going into a detailed explanation of why the information can't be revealed...perhaps the FBI would rather not have a Jonathan Pollard know he's being investigated.   

522(c) refers to investigations in progress, in which the subject either doesn't know he's being investigated or the subject is classified. The existing rule says that, in reference to FOIA requests, that records like these should be treated "as not subject to the requirements of this section". It really isn't much of a change.