Why is this case in a military court?

A Russian military appellate court has upheld the conviction of a civilian from Bashkortostan whose offense was to suggest in a video statement that the Russian Federation should be more of a true federation. Details here. Nine years for urging greater autonomy for ethnic republics and regions? Human rights jurisprudence strongly disfavors the trial of civilians by military courts. One has to assume Airat Dilmukhametov will seek relief on further domestic appellate review or from the European Court of Human Rights.