Thanks for the report. I've already been aware of the problem. There's nothing I could do about it in this mod except for insufficient changes, but I'll tackle this in Minime once I get around to work on that again.
The main issue is a game engine limitation: There is just a single character available in vanilla Factorio, and the devs apparently never expected that there would be a need for several characters. So there was no need to separate the looks (avatars) from other properties (inventory size, health etc.). It's not that we could say "use an engineer class character that looks like compilatron". Bob creates a different character prototype for each class (with all different class tiers considered, about 10 different prototypes), and if you choose a class, exchanges the default character for a new one that looks like the default character but has different properties.
A naive hack would be to overwrite the graphics for each of Bob's characters with ours. But that would break as soon as other avatar-changing mods are added (not likely in single-player games, but in multi-player games it becomes a problem). Unless the vanilla game allows for easily switching the avatar, this problem will have to be addressed by character-selector mods like Minime by making a copy of each Bob's character with exchanged graphics. So adding another avatar mod (e.g. Gear Girl) means creating 10 new character prototypes and keeping track of what class the player is currently using. (Quite complicated, that's why I haven't updated Minime yet.)
Pushing this forum thread may help to get the developers' attention so that they perhaps make it possible to switch avatars at runtime. For now, you'll have to wait until I've updated Minime. Once I'm done with that I may apply the naive hack described above to "I, Robot" for those occasions when no character-selector mod is active. But we're quite busy at the moment with a major update of "Bio Industries", so it still may be while longer before I get back to this. Nevertheless, it will be taken care of eventually!