I understand that Superman is all about his moral code, but in Time Masters #2, it seemed to me like he was just plain being stubborn. In Time Masters #1 Superman gets a little annoyed with Rip Hunter when Rip tells Superman not to interfere with some dying men they come across. Understandable, Superman wants to help these men because they're hurting and he can save them, but it is also understandable that they're in the past, and saving those men could potentially alter the time line in ways that no one can fathom. In the end, Superman listens to reason and lets it go.
 
In issue #2, Rip is separated from the team, leaving Superman, Green Lantern, and Booster Gold pretty much to their own devices. So what's the first thing they should see? A battle between humans and some other beings. Superman's preferred course of action? Ignore anything and everything that Rip said to do and get involved in this, like right now! Seriously Superman, I get that you're trying to help, but you didn't even take a moment to think that you've no idea what this fight is over, who the bad guy and the good guy are, and what's worse, what could possibly happen if you got involved in an event that's not happening in your own time plane?!
 
Also, what up with Green Lantern? In the first issue he's quick to agree with Rip about messing with the past, but in this issue he throws caution to the wind and goes right after Superman like he doesn't even care. I like Superman, and I'm a big GL fan, I just thought it was kind of funny how despite being aware that their actions can have dire consequences on the space time continuum, they just jump headfirst into the action like they're playing on their own back yard.