Depending on your beliefs about what computation Omega did to choose its policy, the TDT counterfactual comes out as either “If things like me one-boxed, then Omega would put $1m into box B on seeing a blue dot” or “If things like me one-boxed, then Omega would still have decided to leave B empty when seeing a blue dot, and so if things like me one-boxed I would get nothing.”
Depending on your beliefs about what computation Omega did to choose its policy, the TDT counterfactual comes out as either “If things like me one-boxed, then Omega would put $1m into box B on seeing a blue dot” or “If things like me one-boxed, then Omega would still have decided to leave B empty when seeing a blue dot, and so if things like me one-boxed I would get nothing.”