But there’s also the case where X is a copy of you, where cooperating does help, so it seems to be a better choice overall.
There is also a case where X is an anticopy (performs opposite action), which argues for defecting in the same manner.
Edit: This reply is wrong.
No it doesn’t. If X is an anticopy, the situation can’t be real and your action doesn’t matter.
Why can’t it be real?
Because Omega has told you that X’s action is the same as yours.
OK.
There is also a case where X is an anticopy (performs opposite action), which argues for defecting in the same manner.
Edit: This reply is wrong.
No it doesn’t. If X is an anticopy, the situation can’t be real and your action doesn’t matter.
Why can’t it be real?
Because Omega has told you that X’s action is the same as yours.
OK.