It should be noted that there is a big difference between NON POWERED and HOT SOCKETING.
The leakage current referrend to is for a part on a board that is "Hot Socketed" onto a backplane, as an example. In that case, the initial power for all the I/O and Internal power pins of the FPGA will initially be zero - but begin to rise as the power supplies ramp up.
This is Hot Socketing.
It is very different that a part that has I/O connected to other parts but is NOT powered at all.
I recall that there is a note somewhere mentioning that if the Vccio of the bank the pins are located in is NOT powered, then the leakage current may be considerably higher.