Itsuki Kurogane has the power to choose the Prime Minister. He did promise Akaza the job, after all. Ergo, he must be aware of the current prime minister's machinations. While it doesn't excuse his actions, it does explain them in that he doesn't want his son in the cross-fire. Still, this is a pure case of "the cure being worse than the disease" and since the current prime minister has no qualms regarding civilian casualties, a complete exercise in futility, especially considering that he has no qualms against Akaza outright killing Ikki.
The fact that Kirihara can turn totally invisible and undetectable can cause a lot of Paranoia Fuel about potential attempts at revenge and Power Perversion Potential. The revenge wouldn't even have to be physical, since he can just spy on Ikki and Stella and discover any of their embarrassing secrets or take embarrassing photos of them. This leads to even more horror when Vol 3 reveals that the Kurogane clan conspired with Kirihara to ruin Ikki's school life and that the clan is launching a smear campaign against Ikki.
Related to the above. The series has shown that Ikki's enemies have no fear of using altered photos to entrap him. Kirihara doesn't even have to take intimate or embarrassing photos. He can take innocent photos and have them altered for maximum damage.
Since the Yui household only raises its children to be psychotic assassins, and they all are constantly looking for an excuse to kill, with their lives in constant peril since age three, where do their children come from?
Ikki mentions that during New Year's parties, his parents would lock him up in his room and tried to pretend he didn't exist. It's heavily implied that their goal was to mold him into a Hikikomori with no willpower for social interaction so they could easily control him and hide his existence as an F-Rank Kurogane.
It's unlikely that Ikki is the only low-ranking Blazer to keep up with his peers, especially with swordsmen like Kaito Ayatsuji around who aren't even Blazers. It makes you wonder if they too were targeted by officials who wanted to "protect" the ranking system.