MessyLife
D multiple reasons 1. The scene is shown that Kabuto already met the others and already showed a "good" guy persona to everyone here, so if Shinji does something unnecessary or aggressive, he might become the center of attention again specially in a room filled with genin teams from other villages 2. Kabuto might have a suspicion that sayuri told us everything and if we react it may confirm his suspicion and give him more reasons to go after us or tell orochimaru to kill us since he might think we know more than we should 3. It will give a bad "first" impression to the other konoha teams since they think Kabuto is a "nice" guy ( probably except shikimaru), Aka lowering relationship points with the others although some may argue why should we even bother, well let me remind you they are the generation who will be facing a lot of heavy events, so it's better to give them a friendly attitude by being humble, since we can already see Yamato give so many benefits to shinji due to max relationship bar, we can assume to receive at least below that from the others besides They will be the meat shields who will stand before the major events so shinji doesn't outright die and they are future powerhouses ( clan leaders etc)
D. Shinji seems to have understood that Kabuto and Sayuri are somehow related. Based on what Kabuto says, Shinji will try to guess his stance towards Sayuri and the team. Also, even if his record of missions is known, it will still give the impression that he is average or somewhat above average, but still very below of his current abilities.