I wasn't upset about nor did I question Tistoria's ability to do as she does. I was upset about how stupid the choice is. The MC's group sprung out of basically nowhere, had a couple merits working darkly and immediately got invited into internal affairs. They could be literally anyone like a foreign spy and it's not clear what their intentions are either. It seems like an insanely big risk to just involve them. Additionally, her threatening the group implies she has the means to threaten them, i.e. can overpower him/them, which we obviously see, Tistoria could cut down the MC at the drop of the hat if she wanted to while they are talking. This further brings into question why you would invite them if they seemingly aren't that strong of an asset, especially considering the unknown background. It's a lose-lose in most scenarios but the very single scenario that the mc's group is loyal and really helpful, which she has absolutely 0 guarantee of.
On the other hand, the MC is equally dumb. The moment he left the immediate vicinity of the castle and Tistoria, he was out of danger. At this moment in time, his crew should be entirely unknown because they wore masks and outfits. He could split with them and just leave the kingdom, rebuild there or heck, meet back up with his crew across the border if he really wanted to. Even if he assumes that he is being followed by assassins or whatever to watch him, after leaving he has full disposal to his army again, which he could use to escape again. Which brings me back to this being really weak characterization because everything that happens relies on both of these characters to just make the worst choices known to man.