None of the subcontractors could do the job themselves, so having one firm manage the contract may be fairly efficient. Much easier than sending out RFPs for 20 different tasks on the same project and then having to get them to all work together nicely.

Makes it easier to deal with that large amount of data there is. As long as the overall objective is clear ("enhance government transparency with structured public data") then it's not a huge problem to sub-contract it.

It's not indirection, it's delegation. A single company cannot handle all the political departments and regional divisions on its own.