It would be the natural outcome for her to be susceptible to James' lies and advances if she doesn't trust the MC because of his decisions. It won't happen though because the dev doesn't want to deal with the massive headache that will follow when people cry about it.
This game was originally a dual protagonist thing where you control the girl as well. Turned into male protagonist and then walked back on the initial plans which was likely going to involve some shady people like James being threats if you don't play it right. It's questionable if even Grace would get more stuff like that one scene. The dev is more malleable to "criticism" than most. But hey, the game isn't doing too bad on patreon at the moment so more power to him.
It's just weird that the James character is a relic from the initial conception of the story and pretty much only functions as a red herring in the current iteration. All his talk about corrupting the female cop has no bite when the player knows that the dev is reluctant to let him succeed. If the dev wanted to make this safe for kids, it would have been wiser to rewrite James' character to be something other than the typical NTR antagonist. There are many different ways to make an unlikable character without giving false NTR vibes.
