I mean, it would feel in bad taste to stick Superman on a planet where he's weakened just so his fathers' greatest enemy, who he's never even met up...
I think Jordan definitely wanted to let Lana in for selfish reasons because he wants to tell Sarah and he thinks it's the only chance of reconciling...
I guess if Alexei was seen with loose lips and that someone would look too deeply into the Black Widow program but the movie couldn't seem to commit...
Though much is taken, much abides; and though
We are not now that strength which in old days
Moved earth and heaven, that which we are, we are,
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.