It's a pattern. This is the same kind of response the EFF got to its FOIA requests about NSLs (national security letters). They were sent back a pack of blank pages as all the text had been redacted. When the ACLU issued a request to the FBI on GPS tracking activity, they were sent back 111 blank pages.
I should hope so! The government is rather more regular than a particularly noisy lab experiment.
Now, as to what it meets the hurdle for statistical significance for . . . well, I personally prefer to avoid conspiracy theories when possible. So I'll just be keeping an eye open for more information.
It proves that they responded to this FOIA request by releasing a blank document. There are many different possible reasons why they released a blank document, but that's another question. (One which we can hopefully answer by examining the history of previous FOIA responses, but still another question.)
For proof that there's a transparency problem, I'd want to look at hundreds of FOIA requests across 10-20 categories, content of news conferences and press conferences, level of press access to government officials, responsiveness to press inquiries, responsiveness to Congressional inquiries, and I could probably think of a few more things if I put more time into it. Then I'd want to compare that to data from previous administrations.
Yeah it's a little weird, but out of the context of other FOIA requests it doesn't make much of a point.