im going to guess either they dont know or they know they dont have the rights to take it down. He's getting them from presumably the VolleyMetrics site (a website for teams and coaches) so the VLeague may not be able to do anything. (But its probably they just dont know hes posting them)
I hope he keeps posting and hope it lasts. Japan isn't very good at putting things up, but they're masters of getting things taken down