Maybe Zod thought the climb to the top of Lexcorp tower would kill Lana?

No? Then I'll have to go with a Lexian "grand romantic gesture" like LaT because Lex couldn't know what would happen to the city.

As for what Zod wants with Lana, could be partly Lex's desire shining through, could be he's been locked away for a long time and he's desperate. Cause yeah, desperation would explain a lot.