@herz i've been laughing my ass off with this manga and i definitely love the characterizations of the protagonists. But there is being flawed/childish and there is being an out-of-character moron. Tachibana isn't the typical 14y old isekai protagonist that use the POWA OF FRIENDSHIP AND LOVE.
He is a freaking 32 years old worker.
And when Jinguuji points out that "bringing the crown heir of a kingdom without any kind of fighting ability with us in our extremely dangerous quest (comedy manga or not they ARE going against dangerous people) because she is sick of being cooped up in the castle" is a SUPREMELY STUPID MOVE he isn't being overanalytical or insensitive. He is being a normal average adult that realizes when a teenager is making a stupid proposition.
The princess is tired of her secluded life? Fine, it's a valid complaint, but there are dozens of different ways for her to have a more active life without having her as a dead weight and endangering the stability of an entire kingdom.
I could somewhat accept an actual teen not realizing this, but from an adult it's simply out of character. And i personally DETEST when an author makes someone act out of character just for the sake of some cliche/gag.