It does seem like EA might be able to sue the people who sell hacks for BF2, but it wouldn't be easy. First they'd have to find them, and the hack-sellers might be outside the US. Then EA would have to show that the hack-writers violated the end user license agreement for BF2, which probably says users aren't allowed to disassemble or reverse-engineer the program. And then EA would have to show it was harmed by the hacks.
I don't know if hack-writers violate BF2's end-user license agreement. Depending on how they go about writing hacks, they might not alter or even disassemble the BF2 software. It wouldn't be necessary if they just create separate programs that send input to BF2 or that send data to the game server. They probably capture and alter web traffic between the program and the game server but it's hard to believe EA could forbid users from looking at data their own computer is sending and receiving from the internet.
It might also be hard for EA to show it was harmed by the hacks. Its reputation has probably been damaged, but EA might have to show it has lost sales due to hacking programs.
I don't know if hack-writers violate BF2's end-user license agreement. Depending on how they go about writing hacks, they might not alter or even disassemble the BF2 software. It wouldn't be necessary if they just create separate programs that send input to BF2 or that send data to the game server. They probably capture and alter web traffic between the program and the game server but it's hard to believe EA could forbid users from looking at data their own computer is sending and receiving from the internet.
It might also be hard for EA to show it was harmed by the hacks. Its reputation has probably been damaged, but EA might have to show it has lost sales due to hacking programs.