Just give my 2 cents:
First, game.exe in MV is basically just a renamed version of nw.js, so it is not MV. The game.exe is just a browser like Chrome or Firefox that is used to run your MV games, it is not the MV engine itself. It is very different with game.exe from previous Maker until VX Ace which is a RGSS Player that was build on top of Enterbrain proprietary technology.
Second, most of RPG Maker MV engine is build on top of open source technology under free software license, including javascript engine (V8), rendering engine (pixi.js), and even the rpg core engine itself is under MIT license, see
https://github.com/rpgtkoolmv/corescript.
Third, if editing game.exe icon is truly prohibited, you can just replace your game exe with nw.js
here . Use same version as your MV game.exe or above, then renaming it as your GameTitle.exe and changing its icon using resourcehacker. Doing this is pretty much same as running your game inside different browser Engine such as Chrome and Firefox which is perfectly fine.