This story just keeps getting better. There is either a grand nefarious plot, or worse, horrific incompetence. I just can't find a third possibility.
The level of misinterpretation of FOIA among FOIA officers, lack of domain knowledge, intentional delays and reject-if-possible mentality makes these things very difficult. Total incompetence.
Though, if you find yourself close to something juicy, you can bet your ass a lawyer will swoop in and find something technically wrong to prevent information from being released. Chicago did that to me eight months in by saying "We don't use VoIP, so your request is void." after the state's attorney general's office told Chicago to give me the info. I'd consider this mildly nefarious.
[0] As far as I'm concerned, "unduly burdensome" is just another way of saying "we're not clever enough to get that information, so you're going to have to come up with a clever way on your own, with 1% of the information we have".