Tiara was literally trying to kill her
and she was well on her way to succeeding.
At no point did Tiara even give a hint that she cared about Yuri's status,certainly not when she was shooting her, and definitely not when she said she would make her "blossom".
Kirin case is just an inconsistency in why a revolutionary actively trying to create a rebellion should care about the status of a member of the Z empire.
he could kill everyone (so no witnesses)
or at worst kill her and blame it on the LPB and PB family
Plot armor is wild here