Lying is a strong charge. I would be ambivalent whether the problem here is lying or prelest: the report did not suggest that the visionary warded himself with the sign of the cross, as has often dispelled visions sent by the Father of Lies.
Of course the reunion of ROCOR with Moscow, and thereby full communion with the rest of the Church displeases the Evil One. It would not be surprising if a false vision were visited on one of those inclined to schism.
good point, though I'll admit a bias in having read other reports on what 'ROCOR-V' folks have done to advance their cause... But certainly the possibility that he thought this vision was real is strong and I'd prefer not to think he was lying...