Lukas felt he could defeat Emma and Calvin. However, it would undoubtedly take quite some time. Calvin Lee, long renowned in the dark world of Handway City, apparently possessed fighting skills beyond what Lukas had known so far.
Interestingly, there had been several reports that Calvin Lee had been badly beaten after defeating some gangster groups. Yes, he did defeat them all by himself. However, with the fighting skills displayed now, he shouldn't suffer severe injuries if he only faces small gangster groups.
Working together, Emma and Calvin would be quite troublesome, and their fighting arena was narrow. Moreover, battling in an old elevator felt risky, as the lift might not withstand the wild movements of three people fighting inside. Lukas couldn't accept the risk of the elevator falling and senselessly killing all three of them.