For the misbehavior of Nobuhide, it is certain that his parents and family were hugely responsible, but as far as Nobumori was doing his duty, it cannot be a reason big enough for the banishment.
信栄の行状が悪いことについても、たしかに親や一族の長としての責任は大きいが、信盛が職責を果たしている以上、追放の理由になるほどの問題とはいえない。