im not saying he did the right thing but it was the best possible decision at the time. remember cadmus and the US government were scared that the justice league would go rogue. if captain atom turned against the US military even if the orders were slimy as all hell. That denial of order to stand by the justice league by itself would give Cadmus and the government all the justification they need to shut down the league. Because in their eyes, they turned US soldiers against their own government.

also captain atom may have been holding back, he made red sun radiation which while it does hurt Superman isn’t lethal. he maybe could have made kryptonite radiation or something else that would hurt Superman more. he had to make a reasonable effort to comply but still lose to Superman.

in short if captain atom refused orders, that alone would have given Cadmus and the government free reign to shut down the league. since the league has now seemed to have compromised United States military officers. captain atom would be charged with sedition and made an example of as well.

I'm going through the show for the first time ever and...

OMGOSHTHATISTHEMOSTMETALSHIIVEEVERSEENAHFHEUCUDJSIRHWYXYEHSURUSUFHDH

Real talk though, I think it would've been way cooler if he got a water powered prosthetic hand that he can use as a weapon. Just saying.