This is one way to fix the "Easy Anti Cheat not Detected" which prevents the game from opening.
Manually Installing Easy Anti Cheat
One way to fix this issue is to manually install Easy Anti Cheat if for some reason it didn't automatically install itself (Like with my game).
Go to: \Steam\steamapps\common\Rising Storm 2\Binaries\Win64\EasyAntiCheat
And start the program EasyAntiCheat_Setup.exe (This installation requires administrator access).
Open up the tab and scroll down to Rising Storm 2 (it's in alphabetical order) or type in Rising Storm 2.
Click Install and just go through the installation steps. Then just re-open RS2 and that should be it.
Of course, there could be cases where this doesn't fix it, in which case I'd suggest uninstalling EAC and verifying the integrity of your files via steam to reinstall it and try this again.