The thing is Tashi has 0 ranks in Bluff and only +1 charisma mod. So Hana would know instant he was lying (she is after all part of intel corps so she has sense motive higher than Tashi is in lying). So if Tashi would go tell even indirect lies, she would know Tashi is holding back information and she may go serious interrogation and that's not fun.<br/><br/>Also note Tashi just gangbanged her, she may go tell her clan elders Tashi raped her and that can cause lot trouble for Tashi and his clan. Even then when it would be digged up why whole scenario started (why Hana lured Tashi fuck her) and if Hana reveals Tashi knows the Kage Bunshin, Tashi will off hand be tortured the information out.<br/><br/>So Tashi was screwed by the point when he used Kage Bunshin in front of Hana, now choice is 'nice way' or 'hard way' of interrogation. Tashi knows that situation is serious as any signs of great village techniques leaking off is serious matter. It's up to kage or village ANBU to decide is Daimyo considered to be only watched or eliminated (and considering present climate they likely just go more watchful mode and likely do own investigation regarding Daimyo how he would had got hands on the techniques, as Tashi's answer does not reveal that). Konohan may not decide 'murder all shinobi who know Kage Bunshin' but they likely want full list of people who know it so if they happen fall in battle their bodies are recovered and properly destroyed so techniques may not be stolen. After the conflict Konohan may ask some fines or some measures to Tanigakure either stop teaching the technique any further shinobi in the village (as the knowledge has already spread). Or as old saying goes 'keep friends close but keep potential enemies even closer to you', it may result Konohan form<em>tighter</em>alliance with Tanigakure so they can monitor things better from them.<br/><br/>Also Konohan is going to war vs Suna for sake of Tanigakure and alliance they have with said village, so the Kage Bunshin knowledge in Tanigakure may had come to pass some point during the war and that may had resulted ugly conspiracy theories, so Tashi's confession can save a lot of trouble in moment where further trouble is no longer wanted/needed.<br/><br/>Edit; Also what comes to true Red Eyes, Tashi is not exactly good terms with his own clan despite his prestigious status in there. He was practically house grounded for two years before Daimyo took him as his personal bodyguard. Considering Tashi already 'donated' plenty of sample already he may give hair and blood sample. He would likely ask Hana to share her medical team findings about Tashi's blood and genetics with Mibu clan (as Konohan has off hand superior medical facility and experts to analyze such things). So in sense giving Konohan genetic information of true red eyes may be beneficial for Mibu to discover how 'duplicate' it. Reason why it has not been done before was because last true red eye user was around +100 years ago and Mibu clan was freshly settled in to Tanigakure and may had been too paranoid to share anything with any other clan/village (and so same paranoia hinders Mibu ever recovering purity of their bloodline).