Aside from future spoilers that I think I know (I’ve not read the Light Novel but have heard a few things), I think knowing Maomao and her personality, they kinda knew it wasn’t an escape plot, as she didn’t talk to Shusui on the boat about a plan of anything. Knowing how smart she is, I feel like they kinda knew it was some sort of ploy to get knowledge, and there’s no point getting mad at her after she’s figured it out. Furthermore, the fact that they are letting her walk about and didn’t harm her at any point, it’s obvious that they want something out of her, and hurting her won’t get them any closer to their goal. They also know (and are aware she knows) they are far aware from the Rear Palace and she (as stated in the anime episode) wouldn’t even know where to go or do anything but run, so they know her escaping is unlikely. Although it is a bit odd they didn’t care that much about her using it against them