mainly because the results would be undeniable
Would they? what if the network is being controlled by the goverenment it self? 51% attack would be an easy way for them to manipulate the results... Unless they use a 3rd party blockchain like ethereum. There is nothing stopping them to manipulate the results.
Knowing how the Japs operate, I don't think they have the guts to manipulate election results, or if ever the doubt arises regarding manipulation, I'm sure they already have a plan for anti-fraud in their elections. Sure that there always is the possibility for a 51% attack on a decentralized blockchain, but if the network itself is hidden and requires some credentials before being accessed, I'm pretty sure there wouldn't be any problems.