That game launch was definitely not a success but that's beside the point. It could've been the best game ever and I still wouldn't care. The matter at hands focus on the creation of a game based off AA2.
In the matter of the rip-off scene, it can be compared to PU:BG vs Fortnite (
https://kotaku.com/battlegrounds-developer-attacks-fortnite-for-replicatin-1818654436). The US Army doesn't own the style of play. Can you imagine the government suing EA for having an army-based game? I should know this by heart but I dont, not for games anyway: How long can a company claim rights for ripoff?
Ethics really isnt the issue, the army let go of the development and support therefore they should allow other people to take from where they left off. This has happened to a lot of games. In fact, if done correctly, they might even recognize the efforts and jump to help or fund again. I don't know if USA's known to do that but some european governments and high authorities have jumped into similar situations (to help and collect fees eventually). With WW3 fast-approaching, this might pickup again.
I will repeat myself: if done right, it doesnt even matter. If its done right, the game mutates. If done right the game isnt the same because if it became the same, why pick up the project or why would the players go there? People are afraid of change.