negates the ability? just because they have the ability to do so doesnt mean sasuke can do it to bm mode and if you didnt notice naruto and kurama have better connection now and are more in link.And Kyubii plays zero part in this sharinghan shuts that down and speaking of which that reminds me sense bijuu mode comes form the power of the kyuubi and uchihas have the power to control them that negates that ability to go bm and even if u try to claim not sasuke back when he made his first appearance in shippuden went into narutos head and stopped his discussion with kyuubi meaning he can literally break their connection
that was when naruto and kurama hated each other and they werent any connection.
plus its assumption that sasuke can stop kurama right now.